ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 981 



lower epithelial layers, where they were most abundant, even to the 

 surface, where they seem to form mucous corpuscles. In shape, both 

 of leucocyte and nucleus, there was evidence of the influence of the 

 pressure to which they were subjected in their migration between the 

 epithelial cells, and the quaint shapes of the nuclei may possibly, he 

 suggests, in some cases betoken direct division. 



Comparative Histochemical Observations on Glycogen.* — Dr. 

 D. Barfurth believes that the origination of glycogen from breakinc- 

 down albuminoids or from still more complicated substances is 

 rendered probable not only by the feeding experiments of various 

 physiologists, but also by the following facts : — 



1. Glycogen is found in all classes of animals and in all kinds of 

 tissues ; this shows that it is a normal product of the metabolism of 

 the cell. 



2. It is widely distributed and largely stored up in foetal tissues. 



3. Hairs of a tuft may differ in size and growth, and those that 

 are best grown are richest in glycogen. 



4 & 5. The presence of glycogen in cartilage and in secreting 

 glands is animadverted on. 



6. It apjjears to have some relation to muscular force. 



B. INVERTEBRATA. 



Phosphorescence of Marine Animals.f — Pi'of. W. C. M'Intosh 

 deals with this subject in his address to the Section of Biology of 

 the British Association, and gives an historical and descriptive 

 summary of the various animals in which phosphorescence occurs, 

 followed by some general remarks. 



The causation of phosphorescence is complex. In one group it 

 is due to the production of a substance which can be left behind as a 

 luminous trail, clearly pointing to other causes than nervous agency ; 

 in certain Annelids, on the other hand, it is purely a nervous action, 

 probably resembling that which gives rise to heat. 



As to the purposes of this provision, which by some has been 

 connected with the special economy of the deep sea, it is to be noted 

 that phosphorescent animals do not appear to be more abundant in 

 the depths of the sea than between tide-marks or on the surface, 

 the latter perhaps presenting the maximum development of those 

 exhibiting this phenomenon. Very many of the young that have 

 been indicated as so brilliantly luminous become surface-forms soon 

 after leaving the egg, and thus at their several stages more or less 

 affect the three regions of surface, mid-water, and bottom. 



A survey of the life-histories of the several phosphorescent groups 

 affords at present no reliable data for the foundation of a theory as to 

 the functions of luminosity, especially in relation to food. No phos- 

 phorescent form is more generally devoured by fishes and other 

 animals than that which is not, and, on the other hand, the possessor 



• Arch. f. Mikr. Anfvt., xxv. (1885) pp. 261-404 (4 pis.)- 

 + Naturo, xxxii. (ISHf)) pp. 470-81. 

 Sftr. 2.— V(ii.. V. 3 8 



