170 



Short Notes and References to new Technical Methods ) 



Some data concerning the cultivation of young and adult Amphibians, 

 P. D. Nieuwkoop. Hubrecht Laboratory, Utrecht. 



The Triturus species taeniatus, cristatus and alpesttis are our most 

 suitable amphibians for experimental work. The adult animals are only 

 available during spring-time. We kept them, however, with success 

 during summer-, autumn- and winter-time in rather flat aquaria made 

 of a mixture of cement and gravel, in a layer of water of 10 — 15 cm. 

 In these closed aquaria an island of stones and tussocks of moss was 

 built. A series of these aquaria formed a current-water system. The 

 current water keeps the temperature at a rather constant level and 

 avoids pollution. The animals can be fed on land or in the water. They 

 become so accustomed to a regular feeding that they will take also 

 dead food like strips of liver and meat, which is a great advantage 

 during winter-time when living food (worms) is scarce. 

 We already got indications that a rise in light, food and temperature 

 can provoke normal breeding reactions. Probably the light plays the 

 most important role. A complete winter-rest seems not to be necessary 

 for a new breeding period. The breeding season can be anticipated for 

 two or three months when optimal conditions are introduced already in 

 winter-time, which fact enable us to extend considerably the period 

 for experimental work. 



We have similar current water systems in use for foreign amphibian 

 species. They are also very practical for subtropical forms as Xenopus 

 laevis, which are cultivated in deeper (25 — 30 cm) wooden aquaria 

 clothed with zinc, at a temperature of ± 25° C. Pollution of these aquaria 

 is strongly reduced by the current water. 



Several species, which in captivity, as a rule, only breed after artificial 

 stimulation with hormones, can probably also be stimulated by a tem- 

 perature shock, but only in case the animals are kept under really good 

 and natural conditions. This holds e.g. for Pleurodeles and Amblystoma, 

 Discoglossus and perhaps also Xenopus. 



Young amphibian larvae are reared with succes in round glass aquaria 

 filled with a rather thick layer of mud and a thin layer of water, and 

 in which water plants guarantee a good oxygen supply. In such well- 

 balanced aquaria the larvae can get a supplementary feeding with 

 Tubifex, Enchytraeus and small worms. 



One should, in general, pay more attention to the ecological conditions 

 under which foreign and native species are living in their natural ha- 

 bitat in order to get really good results. 



General Questions and Announcements '. 



CENTRAL EMBRYOLOGICAL LIBRARY. 



In the general circular of the Hubrecht Laboratory in 1948, we mentioned 



*) 2 ) We ask every embryologist to send us communications for these chapters. The 

 data mentioned here in thia first issue deal casually with the work of the Hubrecht 

 Laboratory only. They only serve as general examples. 



