ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 189 



individuals are stained red or blue." This view does not exclude the 

 possibility that the colour may at times serve to warn predatory foes ; 

 but the conspicuous coloration did not evolve as the result of its selection 

 as a warning. 



Cytoplasmic Inclusions in Germ-cells of Snail.* — J. Broute 

 Gatenby tiuds that the ovotestis of Helix aspersa consists of finger-like 

 diverticula, which are hollow at the lower ends connecting with the 

 hermaphrodite duct, while the upper ends contain more yolk and are 

 filled with metamorphosing male cells. The elements differ in nucleus, 

 mitochondria, uebenkern, and volume according to nutritive conditions 

 and number of divisions. The minute structure is described. Macro- 

 mitochondria and micromitochondria are distinguished, and the function 

 of the nebenkern is discussed. Only confusion will result, we think, if 

 the author persists in the terminology indicated in the following 

 sentence : "The determination of the sex of the indifferent cell seems 

 to be brought about by a variety of causes. The explanation of 

 femaleness by presence of yolk-cells is held to be inadequate, for male 

 progerminative cells also appear in regions choked with yolk." 



Arthropoda. 



Median Eye in Trilobites. — R. Ruedemann calls attention to the 

 presence of a median eye on the glabella. It appears as a tubercle in 

 upwards of thirty genera. There is sometimes a lenticular cavity below 

 a thin cornea ; this may have been filled with sea-water or with some 

 body-fluid. It is comparable to the median eye of some Phyllopods. 

 Indirect evidence for the visual function of the tubercle is submitted. 

 There is least trace of the tubercle in forms with highly-developed lateral 

 eyes ; in genera usually considered as blind because of reduced or absent 

 lateral eyes the median tubercle is most distinctly'developed. 



a. Insecta. 



Nuclear Division in the Adipose Cells of Insects. J — Waro 

 Nakahara makes a preliminary note on amitotic division in adipose 

 cells. There is good evidence that amitosis does not mean the 

 approach of degeneration or aberration, as Flemming believed. It is a 

 kind of nuclear division which, as Chun suggested, secures the increase 

 of surface to meet the physiological necessity which is due to active 

 metabolic interchanges between nucleus and cytoplasm. It occurs in the 

 adipose cells preparatory to and simultaneous with certain metabolic 

 changes in which the nuclei take the role of essential importance, viz. 

 the formation of albuminous granules. It appears that acidophile 

 granules are extruded from the nucleus into the cell-body, forming the 

 characteristic albuminous granules. 



* Quart. Journ. Micr. Sci., Ixii. (1917) pp. 555-611 (6 pis. and 5 figs.). 

 t Proc. Nat. Acad. Sci. U.S.A., ii. (1916) pp. i231-7. 

 I Anat. Record, xiii. (1917) pp. 81-5 (11 figs.). 



