ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 633 



In the more speculative part of his paper, Brornan expresses his 

 belief that these atypical sperms may function in fertilisation. He 

 attaches particular importance to those with one head and two tails, 

 which, he suggests, may be responsible for twins from one ovum. 



Fertilisation in the Bat.*— 0. Van der Stricht has had the good 

 fortune to be able to study the behaviour of the spermatozoon in the act 

 of fertilising the ovum of Vespertilio noctula. The entire spermatozoon 

 penetrates into the interior of the vitellus ; it may enter at the pole 

 where the polar globules are detached, or at the opposite pole, and 

 probably at any spot. The tail persists a very long time beside the head, 

 after the latter is transformed into the pronucleus, even on to the forma- 

 tion of the first cleavage spindle. A spermaster is formed around a 

 central corpuscle — the spermocentrum, and reaches to the anterior end 

 of the portion which connects to the tail of the spermatozoon. No 

 rotation of the head through 180° was observed. 



Epithelial Structures on Parrots' Beaks, f — A. Ghigi has ex- 

 amined a series of embryos of Melopsittacus undulatus. The epitrichium 

 is most developed on the dorsal surface, and least ventrally ; comparison 

 with other birds shows that its distribution is very variable, as is also 

 the distribution and quantity of ceratohyalin in the individual epi- 

 trichial elements. 



The " egg-tooth " consists of many superposed strata of denticulate 

 cells with very distinct and stainable nuclei and granular cytoplasm. 



The papillae of the beak are dermal and epidermal elevations, ex- 

 tending the surface which forms the horny investment of the beak and 

 thereby affording greater strength. 



The dentition is represented, as Rose, Carlsson, and others have 

 shown, by epithelial laminee on the jaws, and that of the upper jaw in 

 parrots attains a notable degree of development, and persists some time 

 after the bird is hatched. 



Regeneration of the Lens in Chick Embryos.:}: — D. Barfurth in 

 co-operation with O. Dragendorff has shown that the embryo of the 

 fowl shows characteristic regenerative processes on the internal wall of 

 the optic cup and can form a new lens. The regenerated lens is closely 

 connected with the margin of the optic cup, therefore with the sub- 

 sequently formed iris margin. The operations destroyed the normal 

 ectodermic primordium of the lens and injured the subjacent portion 

 of the developing optic cup. It seems most probable that the margin 

 of the optic cup affords the formative tissue for the new lens. 



It appears from the above that the embryo-bird has a regenerative 

 capacity which the adult almost entirely loses, which corresponds with 

 what Barfurth has previously observed in regard to Amphibians. Bar- 

 furth inclines to say that regenerative capacity is an original and 

 intrinsic power of organisms, and he does not think that this view is 



* Verh. Anat. Ges., xvi. Vers, in Anat. Anzeig. Erg'anzungshft., xxi. (1902) 

 pp. 163-8 (1 fig.). 



t Anat. Anzeig., xxi. (1902) pp. 145-63 (8 figs.). 



% Verh. Anat. Ges., xvi. Vers, in Anat. Anzeig. Erg'anzuDgshft., xxi. (1902) 

 pp. 185-99 (13 figs.). 



