178 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Eyes of Chrysochloris.* — Georgina Sweet publishes a study of the 

 Chrysochloris hottentota and C. asiatica. The eyes of the two forms 

 agree in almost all details. The eye has sunk only into the dermis, and 

 is surrounded by the hair-roots. The conjunctival sac is well developed, 

 and also generally the lachrymal gland, the duct of which opens into 

 the sac. From the sac in most cases a cylindrical tube leads to the 

 exterior, but from its direction it can be of no use as a path for light-rays 

 giving rise to vision. The eye muscles are quite absent. Sclerotic lens 

 and choroid are represented by the fibrous schlerochoroid. Lens and 

 iris are very degenerate though quite recognisable. The vitreous 

 humour is absent. The pigment layer of the retina is thick posteriorly, 

 and absent anteriorly. The retinal layers are, in most cases, clearly 

 distinguishable, very little degeneration being apparent in the outer 

 ones. The layer of rods and cones is more or less distinct. The optic 

 nerve was found in the adult specimens examined, though the ganglion 

 cell layer is the most degenerate part of the retina. 



As regards the position, the eye in Chrysochloris is not, even after 

 the hair is shaved, generally visible from the exterior, as it is in Scalops 

 and Talpa, but it is comparatively superficial in contrast to that of 

 Rhineura and Notoryctes. The eye of Chrysochloris as a whole is 

 distinctly more degenerate than that of Talpa or Scalops, but very 

 much less so than that of Notoryctes. It is without doubt of no use 

 for vision, and it is improbable that even degrees of light can be 

 detected by it. The gland secretion can only have its usual function 

 of keeping the conjunctival cavity free from foreign matter. 



Variations in Hyla aurea.f — Georgina Sweet records a number of 

 variations in this Australian frog, e.g. a vestigial arch between the 

 systemic and the pulmo-cutaneous ; looping of the veins (dividing and 

 re-uniting), especially in the mandibular, external jugular, and femoral 

 veins ; indications that the sacral plexus is moving forwards ; fusion and 

 distortion of vertebra? ; and so on. 



Hybrid Newts.} — Heinrich Poll artificially fertilised the ova of 

 Triton cristatus Laur. and T. vulgaris L., and conversely. A large num- 

 ber of ova began to develop, but most died in early stages. Only a few 

 became fully formed larva?, a hybrid of T. vulgaris $ and T. cristatus 9 , 

 and seven of the converse crossing. A hybrid which accomplished the 

 metamorphosis showed a striking mixture of paternal and maternal 

 qualities, and some resemblance to T. vittatus. It may be recalled that 

 T. blasii de l'lsle was shown by Wolterstorff to be the hybrid of 

 T. cristatus and T. marmoratus. 



Thymus of Teleosteans.§ — J. A. Hammar publishes a study of the 

 thymus gland in Teleosteans. For his investigation he used many 

 stages of eleven different species, and single specimens of other nine 

 forms. Almost all the specimens were freshly caught. In his account 



* Quart. Journ. Micr. Sci., liii. (1909) pp. 327-38 (1 pi.). 



t Proc. Roy. Soc. Victoria, xxi. (1908) pp. 349-64 (2 pis., 9 figs.). 



t Biol. Centralbl., xxix. (1909) pp. 30-31. 



§ Arch. Mikr. Anat., xxxvii. (1908) pp. 1-68 (2 pis., 10 figs.). 



