ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 303 



fasting or thyroid treatment induces rapid degeneration of the cells. 

 Moderate fasting or moderate thyroid treatment is followed by the 

 appearance of numerous very minute granules in the nucleus, which 

 move out into the cytoplasm into fat corpuscles. This occurs in normal 

 conditions also, l)ut to a less extent. 



Mitochondrial Structures in Primitive Germ-cells of Bird- 

 embryos.* — H. von Bereuberg-Gossler tinds a sort of network or lattice- 

 work mitochondrial differentiation in these cells. It takes the form of 

 a tangle of thin threads in a net or capsule around the centrosphere. 

 It is so characteristic that it may be used as a means of detecting the 

 presence of primitive germ-cells in extra-genital parts of the embryo. 



Hard Tendons of Birds.f — E. Retterer and A. Lelievre have in- 

 vestigated what are often called " ossified " tendons in birds. There is 

 no doubt that the tendons of muscles in the hind leg often become as 

 hard as bone, but there is only a delicate zone with the characters of 

 bony tissue. The main mass of the tendon is due to hypertrophied 

 tendinous tissue ; the cells become very vesicular and the fibres are 

 calcified. Around the vascular canals there is a delicate zone of 

 vesicular cells which takes on the characters of true bony tissue. 



Digital Tuberosities of Leptodactylus ocellatus.|^M. Boidt has 

 investigated the minute structui e of the two swellings on the hand of 

 the males of this species of frog. There is a many-layered horny cap, 

 below this a stratum germinativum, and then fibrillar connective-tissue 

 with blood-vessels and nerves. There is no special glandular development. 



Minute Structure of Retina of Sphenodon.§ — Freda Bage de- 

 scribes the nerve-fibre layer, the ganglionic layer, the inner molecular 

 layer, the inner nuclear layer, the outer molecular layer, the outer 

 nuclear layer, the layer of cones, the layer of pigment epithelium, and 

 the supporting structures of the retina. A detailed account is also 

 given of the sense-cells of the retina, namely, the cones. Of these there 

 are three very definite kinds, viz., the smaller and larger single cones 

 and the double cones. 



Heart Muscle in Reptiles and Amphibians. || — M. Fedele deals in 

 particular with the reticular apparatus and sarcolemma of the muscle- 

 fibres of the heart in lizards, newts, etc. The network of fibres arises 

 in the interstitial connective-tissue, which invests the bundles with a 

 perimysial membrane. It penetrates into the bundles and Ix'comes most 

 intimately applied to the muscle-fibres and their delicate sarcolemma. 



Hair-like Structures in a Frog.lF — Willy Kiikenthal describes 

 remarkable hair-like filaments on both sides of the body and on the 

 outer surface of the thigh of the males of Astylosteryius rohnstus (Blgr.), 



* Anat. Anzeig., xl. (1912) pp. 587-91 (2 figs.). 

 t C.R. Soc. Biol., Ixxi. (1911) pp. 596-9. 

 : Arcb. Nafcurges , Ixxvii. (1911) pp. 80-6 (4 figs.). 

 § Quart. -Journ.Micr. Sci., Ivii. (1912) pp. 305-28 (3 figs.). 

 II Rend. R. Accad. Sci. Napoli, fasc. 1-2 (1912) pp. 1-8 (3 figs.). 

 ^ Bull. Mus. Comp. Zool. Harvard, liii. (1912) pp. 371-6 (5 pis. and 2 figs.). 



