Arr.AX Tapaveris Ì*i:i;ims 145 



plants, which were toniieily (h'scribed as one species, proved to consist 

 out of a huye number of constant elemental si)ecies, it must not be 

 astonishing, that the same occurs with animals and an additional fact 

 here is, that the elemental spei-ies only differ in physiological cha- 

 racters. As there exist also animals which are capal^le of forming- 

 galls on nearly related si>ecies , as is proved by the exi)eriment of 

 Peykitsoh on Aphis and Beyekinck on Rìiodifcs , it is of great 

 imi)ortance to dis<'o\er tliese sorts of animals. 



We tind analogical cases in other ])lant-diseases. There are fungi 

 which only live on one special sj^ecies, others which are more poly- 

 biont. And sexeral investigators have found this. 



In a tbrmer article (1) we treated another point of the gall- 

 (juestion, especially : whether there are in the galls other characters 

 than in the normal i>lants or not. We came to tlie conclusion that 

 the characters of the gall and the plant are the same. We take this 

 opportunity to express <uir regret, that we have not mentioned the 

 ample exjiosition of Küster (13) on this question in his « Fathologische 

 T'ßanzcnanatoiiiic, thinking that he gave in his article in « Flora » (3) 

 his own opinion and in the « Path. Pßdn-cnnnnioiiiic » a review of the 

 theories of other investigators. We hasten to redress our mistake. 



11. Life of the Gall-wasp. 



At the end of May the tirst wasps appear and are soon followed 

 by more. In the beginning of June they come out in large number 

 an<l this goes on till almost at the eiul of the month. 



There are seen many more females than males. W^e kei)t some big 

 galls apart to know if the wasps , which come out of one gall are 

 all of the same sex (»r not. I>ut tliis api»eared not to be the case; 

 there came many 9 ^i^t^ some cf ^^^^ <^t" each gall. 



The wasps are rather small and they walk fast, but do not Hy 



(1) Die Entwickolnng der Galle von IJpiira Inceiis. Reciiicil des Tra v. liot. 

 Néerlandais \. 4. l!)0(i. 



(2) E. KiisTKif — l'afliidonisclic RHaii/i-iiaua touiic Jena l!tu;ì. 



(3) E. KÜSTKK — Beiträge zur Kemituiss der Gallenaimtoinic. IMoia, I!d. ST 1!H)(). 



