502 



SCIENCE. 



[N. S. Vol. XXII. No. 564. 



cell in the female than in the male. The 

 primary factor in the differentiation of the 

 germ cells may, therefore, be a matter of 

 metabolism, perhaps one of growth. 



Edmund B. Wilson. 

 Zoological Laboratory, 

 Columbia University, 

 October 3, 1905. 



- THE GEOGRAPHICAL DISTRIBUTION OF THE 

 BELL-TOADS. 



At the meeting of the Association of Amer- 

 ican Geographers in Philadelphia, December 

 29, 1904, I read a paper on the ' Geographical 

 Distribution of the Discoglossoid Toads in the 

 Light of Ancient Land Connections,' ^ in 

 which I made the following statement : 



All indications point towards the country south- 

 east^ of the Himalayas as the original center of 

 the radiation of the discoglossoid toads, as well 

 as of their near relations the pelodytoid toads. 

 The former are not now found in this region; but 

 that fact weighs but little in view of Ascaphus 

 having remained unknown on this continent till 

 1899, and thus far known only from a single speci- 

 men. 



This statement assumes almost the character 

 of a prophesy in view of the fact that Dr. G. 

 A. Boulenger, a month later, announced the 

 discovery of a bell-toad (Bomhina) in the 

 province of Yunnan, near Tong Chuan Fu, at 

 an altitude of about 6,000 feet. This new 

 species, Bomhina maxima (Boulenger), thus 

 indicates the central form from which both 

 the European and the Korean bell-toads have 

 sprung. Confirmatory of this, it may be men- 

 tioned that the new species in most essentials 

 agrees with Bomhina orientalis and B. salsa, 

 the latter being the more southern and, in 

 my opinion, the more primitive of the two 

 European species. 



The discovery of this species lends further 

 weight to the theory propounded by me for 

 the migration of this genus' in the following 

 terms : 



^Resume published in Amer. Geogr. Soc. Bull., 

 XXXVII., February, 1905, pp. 91-93. 



^ In the resume quoted ' southwest ' through a 

 lapsus or misprint. 



' L. c, p. 93. 



Of the various theories which might be advanced 

 in order to explain this distribution it seems most 

 reasonable at present to select the one which pre- 

 supposes a comparatively late immigration of 

 this genus from southeastern Asia into Europe 

 after a late Miocene land connection had been 

 established — a theory which would account for 

 the failure of these toads to reach Spain on the 

 one side and Japan on the other. 



The supposed original central form in south- 

 eastern Asia has now been found, and the 

 theory to a great extent verified almost at the 

 very moment of its publication. 



Leonhard Stbjneger. 

 U. S. National Museum, 

 Washington, D. C, 

 August 31, 1905. 



hydration CAVES. 



The conclusions set forth in my paper 

 ' On the Origin of the Caves of the Island of 

 Put-in-Bay, Lake Erie,' ^ were based mainly 

 upon observations, made last year,- in Perry's 

 Cave. The conditions, however, which exist 

 on the island, led me to believe that the hydra- 

 tion of anhydrite has played an important 

 role in the formation of all the caves. At 

 that time I was able to visit three of the four 

 caves open to the public, namely. Perry's, 

 Kindt's and the Crystal Caves. Concerning 

 the other cave, Daussa's, the following state- 

 ment was, however, made in the paper referred 

 to above : " But inasmuch as this cave is in 

 very close proximity to Perry's Cave, the above 

 explanation, no doubt, also applies to it." 



During another visit to the island several 

 weeks ago, Daussa's Cave was visited and it 

 was noted that the fitting of the roof and 

 floor is to be observed fully as well in this 

 cave as in Perry's, leaving, therefore, no 

 doubt whatever as to the origin of the same. 



Erom the general topographic features of 

 the island and the mainland in that vicinity 

 —especially that which is known as Catawba 

 Island — one is led to believe that careful 

 searching should reveal more of these inter- 

 esting caves, which difFer so much in their 

 origin and structure from the ordinary solu- 

 tion cave, thaf I would suggest they be termed 



^American Geologist, XXXV., 167-171, March, 

 1905. 



