26 



The arguments for and against this theory are as follows: 



When Stahl published his work on '' The Sexual Reproduc- 

 tion of the Collemacese/' no one was able to refute the assump- 

 tion that the office of the spermatia was that of fertihzation. But 

 it is quite as evident that in all the investigations made by Stahl, he 

 was unable to bring forward any direct proof of this assumption. 

 This latter fact was first clearly stated by Brefeld in his work on 

 *' Schimmelpilze." Now Moeller states that this last mentioned 

 criticism holds also in reference to the two other cases generally 

 cited in connection with that of the CoUemacese, viz.: What is 

 given by Fisher and Frank in reference to Polystigma and Gno- 

 monia. These three instances, he says, are the only ones brought 

 forward by the advocates of the sexual nature of the spermatia 

 of the ascomycetes. Opposed to this view of the subject is a 

 long list of facts which may be briefly stated as follows : 



Already in 1876, shortly before the appearance of Stahl's 

 work on the Collemaceae, Cornu had discovered that in case of 

 several kinds of the spermatia in question, they began to germi- 

 nate and develop into a mycehum, when offered the proper 

 nourishment. Against this evidence of the conidial nature of 

 the spermatia critics at once decided this to be only an abnormal 

 development of a sexual organ whose real function was turned 

 aside by external causes, and they gave as an analogous case the 

 germination of the pollen grain in a sugar solution. 



Next' appeared Krabbe's investigations, published both in the 

 Bot. Zeitung and in the Berichte des Deutschen Gesellschaft zu 

 Berlin. These had special reference to the lichens. From this 

 work it appears that the spermatia produced by Cladonia cannot 

 be considered sexual organs, because the development of the 

 apothecia is shown to be independent of any participation on the 

 part of the spermatia. To evade this evidence of their non- 

 sexual character, the opponents of this theory had recourse to 

 the assumption of apogamy, this being the only possible expla- 

 nation left them. 



Next, the author speaks of the objections raised as to the re- 

 sults of his own work, although he succeeded in bringing the so- 

 called spermatia, not only to germination, but to thallus-forming 



