72 O. E. PLATH. 



and Bremus impatiens (by myself) in this country, confirm those 

 of Sladen (1912). l In large colonies of Bremus impatiens, I have 

 repeatedly found a considerable portion of the lower cocoons 

 filled with thick honey and completely capped so that no opening 

 could be seen, even with the aid of a hand lens. 



XII. THE FOOD OF BUMBLEBEE LARVAE. 



In his extensive paper on the hive-bee, 2 Swammerdam (1752) 

 also refers incidentally to some of his biological observations on 

 bumblebees, and expresses the belief that the larvae of the latter 

 feed on the wax by which they are surrounded, since, in his 

 opinion, it seems improbable that the adults open the wax 

 covering to feed the larvae. But Huber (1802) found that this 

 is precisely what the adults do, and that the food of the larvae 

 consists of a mixture of pollen and honey, and not of wax. These 

 observations of Huber (pp. 263-265) were later confirmed by 

 Schmiedeknecht (1878, p. 321) and Hoffer (1882/83). However, 

 several years later, Harter (1890), being unable to observe any 

 such method of feeding, questioned the correctness of Hoffer's 

 (p. 27) observations and came out strongly in support of Swam- 

 merdam's (pp. 194-195) hypothesis. Since, to my knowledge, 

 Harter 's (p. 67) claim has never been denied, I should here like to 

 mention the further positive evidence by Coville (1890) and 

 Sladen (1912) whose observations agree with my own. In this 

 connection, it may be stated that the Pocket-makers, as was first 

 pointed out by Sladen (1899), use a somewhat different method of 

 feeding their larvae, at least those of the workers. This question 

 will be discussed more fully in connection with another paper. 



XIII. ASSISTANCE TO EMERGING YOUNG. 



Huber (1802), Dahlbom (1832), and von Buttel-Reepen (1903) 

 state that bumblebees assist their young during the process of 

 hatching by widening the slit which the emerging bee makes in 

 its cocoon. Not long ago, Wagner (1907) subjected this question 

 to the experimental test. He isolated some cocoons of Bremus 

 lapidarius and found that the first worker which emerged 

 although two days old did not pay the slightest attention to the 



1 Since writing the above, I have discovered that the French Abbe Noel de 

 Pluche (1764) also made this observation. 



2 This paper (cf. Swammerdam, p. vi) was completed in 1673. 



