OCR Text |
Show 1889.] MR. F. E. BKDDARD ON iEOLOSOMA TENEBRARUM. 55 pi. 9. fig. 9), in many of which the pigment is collected into a globule lying in the middle of the cell; this globule is, according to Moseley ("On Stylochuspelagicus, &c," Quart. Journ. Micr. Sci. vol. xvii. 1877, p. 30), of a fatty nature, which is a further point of similarity to JEolosoma. A resemblance-perhaps of greater importance-is shown to Gtenodrilus; this genus consists of three species, in all of which the integument is dotted over with coloured spots. In Gtenodrilus monostylos (v. Zeppelin, " Ueber den Bau und die Theilungs-vorgange des Gtenodrilus monostylos,," Zeitschr. wiss. Zool. Bd. xxxix. p. 617) aud in Gt. pardalis (v. Kennel, "Ueber Gtenodrilus pardalis," Arbeit. Zool. Inst. Wiirzburg, Bd. v. 1882, p. 375) these spots are dark green. In the third species, Ct. parvulus, Dr. ScharfF (" O n Gtenodrilus parvulus," Quart. Journ. Micr. Sci. vol. xxvii. 1887, p. 592) states that the spots are dark green or violet, and that the colouring-matter is carried by an oily substance. I am not quite clear from Dr. Scharff's paper whether he means to say that the colour of these spots in Gtenodrilus parvulus is violet, or whether green and violet spots both occur. In any case, the alternation of green and violet is most suggestive in the light of what has been already said regarding the change of the green pigment of JEolosoma tenebrarum into violet by an alkali: moreover, Prof. Hartog informs me that he observed " claret-coloured " spots as well as green in one individual of JE. variegatum; this fact is evidently of importance. Moseley's observations upon the blue and red colouring-substances of two land-planarians found at Sydney, N.S.W. (" On the Colouring- matters," &c, loc. cit. p. 11), suggest, however, the need for caution in drawing such an inference; he found that the blue pigment of one of the worms was converted into red by the action of acids, and surmised therefore that the red pigment of the other species would prove to be identical with this pigment; but this surmise proved to be incorrect. I have already suggested that the green pigment of JEolosoma tenebrarum may be a respiratory pigment, capable of oxygenation and deoxygenation ; the peculiar reaction with iodine which has been referred to may possibly fit in with this hypothesis. I may also mention that the change in colour of the cells from a bright yellow-green to a dull olive-brown is very suggestive of a corresponding taking up and giving off of oxygen, but I have no positive facts to offer, and the proof is indeed extremely difficult. The blood of JEolosoma tenebrarum is quite colourless at all times. The plasma of the blood of JEolosoma quaternarium and JE. ehrenbergi is stated by Vejdovsky (loc. cit. p. 18) to be colourless ; but he describes cells with branched processes attached to the walls of the dorsal vessel in these species and in JE. tenebrarum, which contain a yellow pigment. This may be haemoglobin, but there are no obser-far as I can remember). I made a few notes upon the worm, which I have unfortunately lost; I hope, however, to have an opportunity of finding the Planarian again. It was not Vortex nor Mesostomum nor Convoluta. |