1148 The Zoologist— April, 1868. 



egg : this, however, might certainly have been laid by the female of 

 the first-mentioned district. In short, on this point I have been 

 unable hitherto to arrive at any positive result. But two eggs of the 

 same female, which I myself found on one day in that district, and 

 which were coloured and marked just alike, both lying in nests of the 

 whitethroat [Sylvia cinerea), one quite fresh, the other a little sat 

 upon; these, coupled with'a very differently coloured cuckoo's egg, 

 which was found on the same day in another district, made me sup- 

 pose that at the root of this striking phenomenon there was a fixed 

 law, perhaps a law which might be discovered. 



I now began to pay more attention to the cuckoo's eggs, and made 

 it my special endeavour to make myself quite certain of every egg 

 which passed through my hands, with regard to the nests in which 

 they were found ; and with that view and to that end I immediately 

 wrote to my oological correspondents, to impart to them my opinions, 

 and to invite them to a careful attention to these circumstances. In 

 a short time I obtained the most astonishing results, part of which 

 I communicated at Berlin and Altenburg,* and some of which have 

 been already published in the ' Naumannia.' t 



In the next place the list is now very much enlarged of those 

 birds which are admitted to have acted as foster-parents of the cuckoo.. 

 Dr. Thienemann mentions the followiug: — 



1. Sylvia hortensis .... Garden Warbler. 



2. „ cinerea 



3. „ atricapilla ? 



4. „ curruca . . 



5. „ tithys . . 



6. „ phcenicurus 



7. „ rubecula 



8. „ arundinacea 



Whitethroat. 

 Blackcap. 

 Lesser Whitethroat. 

 Black Redstart. 

 Common Redstart. 

 Robin Redbreast. 

 Reed Wren. 



* When I communicated to a meeting at Altenburg my experience, further 

 detailed in the text, the Royal Forester Braune, of Greiz, rose, very & propos, to support 

 my previous assertions, by recording facts already touched upon above, and which will 

 be more fully detailed further on — viz. that the cuckoo lays also reddish, dark-spotted 

 eggs, very like the eggs of Hypolais. In Berlin the most distinguished anatomist 

 and physiologist of our time, the Privy-Councillor Professor Johann Muller, challenged 

 me to put together the cuckoo's eggs in the collection lying before me, and to mix 

 them with the eggs of the foster-parents of the cuckoo which were lying near, and 

 then to search again for the cuckoo's eggs, and to arrange them accurately, which I at 

 once accomplished. 



t 'Naumannia,' i. 2, p. 48, 61; ii. 1, p. 4; iii. I, p. 105, 106; 2, p. 203,228. 



