538 §• Abstammungslehre. 



is so great that any influence which could be wrought by such is almost iu 

 appreciable. 8. The little evidence available sbows that young Ceylon birds 

 imitate their parents in their choice of food; but as regards butterflies, the 

 fact that there is no discrimination shown by adults leads one to conclude 

 either that few or no tasting experiments were undertaken in youth, or, what 

 is more probable, that their taste with regard to them is indifferent. 9. It is 

 questionable, and so far as accurate knowledge of one species goes it is de- 

 finitely shown, that that form of mimicry represented by wet and dry season 

 forms (cryptic defence) is not produced for the protection of the species, 

 in as much as many (four) succeeding broods of the wet weather form may be 

 found under dry season conditions without detriment to the species. 



Doncaster (Cambridge). 



1503) Pocock, R. I., (Zoological Gardens, London), On the Palatability 

 of some British Insects, with Notes on the Significance of Mi- 

 metic Resemblances. 



(Proc. Zool. Soc. 3. p. 809-868. 1911.) 



This paper gives a detailed account of experiments in offering living in- 

 sects to various Mammals, Birds and Reptiles in captivity in the London 

 Zoological Gardens. It is impossible to summarize the experiments; some of 

 the leading results are as follows. Several insects showing warning colours 

 are clearly unpalatable, and in general those which are cryptically coloured 

 are more palatable than those which are conspicuous. The insectivorous birds 

 vigorously chased and captured butterflies, and the skill with which the 

 butterflies attempted to elude pursuit is strong evidence that birds are real 

 enemies to butterflies in nature. Different birds showed great differences in 

 regard to the readiness with which they ate unpalatable species, and some 

 beetles and Hymenoptera which were eaten by birds were rejected by mammals. 

 The species which were shown to be unpalatable frequently belonged to 

 genera which are mimicked in Europe or elsewhere, and animals which had 

 attempted to eat Humble Bees but had rejected them when they found them 

 unpalatable refused to touch the similarly coloured Volucella. There is evi- 

 dence that Hymenoptera are unpalatable apart from their stings. The sudden 

 opening of the wings of Vanessa io prevented a lycatcher (Rhipidena) 

 from taking it, and a Bulbul (Pycnonotus) repeatedly pecked at the eye-spots 

 on the wings, suggesting that the colouration of this species is protective. 



Doncaster (Cambridge). 



1504) Müller, R. (Hygienisches Institut Kiel), Mutationen bei Typhus 

 und Ruhrbakterien. 



(Zentralbl f. Bakteriologie I 58,2. p. 97-105. 1911.) 

 Es erscheint heute als erwiesen, daß manche Bakterien eine neue be- 

 stimmte Eigenschaft erwerben können und dieselben auch auf ihre Nachkommen 

 vererben. So beschrieb Massini 1906 zuerst das Bact. coli mutabile. Der 

 Verf. entdeckte sodann ähnliche mutationsartige Vorgänge bei Typhus- und 

 Paratyphusbakterien, sowie gewissen Pseudodysenteriebakterien. Diese drei 

 Bakterienarten wachsen auf Rhamnoseagar unter Bildung von knopfartigen 

 Tochterkolonien, und zwar ist dies ein nie fehlendes Kulturmerkmal dieser 

 Bakterien. Außerdem vollzieht sich eine Anpassung an den Rhamnosenähr- 

 boden, indem die Kolonien auf diesem wachstumshemmenden Substrat klein 

 und zart bleiben. Verf. möchte sich diese Hemmung im Sinne der Ehr Hell- 

 sehen Seitenkettentheorie so deuten, daß gewisse Rezeptoren des Bakteriums, 

 die sonst zur Aufnahme anderer Nährstoffmoleküle dienen, durch den fremden 

 Stoff verstopft und so ausgeschaltet werden. Es blieben wohl manche Rezep- 



