ZOOLOGY AND BOTANY, MICROSCOPY, ETC, 183 



shape of the mammalian erjthroplagtid, the concavo-convex cup being 

 merely an occasional modification. 



Blood-corpuscles of Alligator.* — Albert M. Reese has studied the 

 blood of Alligator mississippiensis as regards the corpuscles. The average 

 dimensions of the fresh erythrocytes were "Z^'ll micra in length, 12*78 

 in width, 4 •17 in thickness. The cytoplasm was transparent, and 

 :seemed to be homogeneous. The nucleus was in most cases ellipsoidal. 

 Hints of amitotic division were seen. There were various types of 

 leucocytes, which are described. 



Fatty Tissue of Crocodilians.t — Ed. Retterer and . H. Neuville 

 find that the fat in Crocodilians, as in mammals, is due to an elabora- 

 tion or transformation of the hyaloplasm of the cells of reticulate 

 connective tissue. The hyaloplasm changes into fatty corpuscles, which 

 are separated by trabecule which stain readily with hf^matoxylin. The 

 adipose cells are bound together by re*"iculate septa, which also stain 

 readily with haematoxylin, and are in part elastic. The perinuclear 

 portion of the cytoplasm of an adipose cell is capable of developing 

 with the nucleus so as to form a blood-corpuscle. 



Time occupied in Mitosis. | — Warren H. Lewis and Margaret R. 

 Lewis have observed the time required for mitosis in mesenchyme cells 

 from embryo chicks four to eleven days old, and cultivated in Locke's 

 solution with or without the addition of bouillon. The time required 

 for the complete process of mitotic cell-division was within the following 

 Hmits : Prophase, 30 to 60 minutes ; metaphase, 2 to 10 minutes ; 

 anaphase, 2 to 3 minutes ; telophase, 3 to 12 minutes ; and the 

 reconstruction period, 30 to 120 minutes ; total, 70 to 180 minutes. 

 A fair estimate would be between two and three hours. In more 

 normal conditions — namely, a four-day chick with the amnion intact in 

 Locke's solution — the division of the smooth muscle-cells was observed : 

 Prophase, 33 minutes ; metaphase, 2 to 15 minutes ; anaphase, 1 to 3 

 minutes ; telophase, 3 to 5 minutes ; and the first part of the recon- 

 struction period, 4 to 10 minutes. It seems very probable that the 

 duration of mitosis is not very different in different types of cell. 



Minute Structure of Retractor Penis-muscle of Dog.§ — Homer 

 Gr. Fisher refers to the discrepant histological descriptions of this 

 muscle. The fact seems to be that the muscle is mixed. In the 

 anterior three-fifths the fibres are wholly smooth, while in the posterior 

 two-fifths the fibres are both smooth and cross-striated. 



Phagocytosis by Osteoclasts. || — Leslie B. Arey finds that bone 

 cells laid bare by the resorptive process may be engulfed by osteoclasts. 

 The phagocytic inclusion of a bone-cell by an osteoclast is described and 

 figured. 



* Anat. Kecord, xlii. (1917) pp. 37-44 (8 figs.), 

 t G.R. Soc. Biol. Paris, Ixxx. (1917) pp. 795-7. 

 i Anat. Record, xiii. (1917) pp. 359-67. 

 § Anat. Record, liii. (1917) pp. 69-79 (2 pis.). 

 II Anat. Record, xiii. (1917) pp. 269-72 (4 figs.). 



