. Experimental morphology. Protoplasm; Growth. §4] PHOTOTAXIS AND PHOTOPATHY 193 we find this capacity for rearrangement of pigment granules, as ExNKR ('89 and '91, p. 104), Stepanowska ('90), SzczA- â wiNSKA ('91), Paekbb ('95), and others have shown. In the higher Crustacea, for example, the pigment granules of the pigment cells surrounding the rhabdome (or "spindle") are, in the dark, below the level of the spindle. Upon illumination, however, these granules migrate (or are carried) upwards, and partly envelop the rhabdomes. I believe it has not been deter- mined what rays are in
. Experimental morphology. Protoplasm; Growth. §4] PHOTOTAXIS AND PHOTOPATHY 193 we find this capacity for rearrangement of pigment granules, as ExNKR ('89 and '91, p. 104), Stepanowska ('90), SzczA- â wiNSKA ('91), Paekbb ('95), and others have shown. In the higher Crustacea, for example, the pigment granules of the pigment cells surrounding the rhabdome (or "spindle") are, in the dark, below the level of the spindle. Upon illumination, however, these granules migrate (or are carried) upwards, and partly envelop the rhabdomes. I believe it has not been deter- mined what rays are involved in producing this result. This response to light is considered to be an advantageous one, since. cu. ep. Fig. 58. âVertical section of a whitish-yellow dermal papilla; lettering as in Fig. 57. p', processes of black pigment cells containing no pigment. (After Keller, '95.) the pigment thus cuts off side rays from the perceptive organ â the rhabdome. It is interesting that we should find cells containing two so diverse kinds of pigment as chlorophyll and the retinal pig- ment responding to light in so similar a fashion. In most of the cases, if not all, this response is an adaptive one. 7. The Migration of Pigmejit Cells in the Metazoan Body. â It has been shown, apparently first by Engelmann ('85), that the pigment cells of the retina vary their movements with the light. Thus, when a strong light is thrown upon the retina of the frog, the pigment cells send out pseudopodium-like processes between the rods and cones, whereas in the dark the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Davenport, Charles Benedict, 1866-1944. New York, The Macmillan company; London, Macmillan & co. , ltd.
Size: 1873px × 1335px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1897
