14 Spermogonia and Spermatia. 



continue their further development. In a paper by Arthur 3 on the Taxo- 

 notnic Importance of the Spermogonium, he shows that, in the first pla^t, 

 ihe presence of the spermogonium, along with its associated spore-forms, 

 gives important information regarding the length of the life-cycle. Thus 

 he concludes that if spermatia and uredospores arise from the same 

 mycelium, aecidia do not occur, and if spermatia and teleutospores thus 

 arise, neither uredo nor aecidio spores will occur. There are cases, how- 

 ever, in which the spermogonia are found in association with both uredo 

 and teleuto spores, as in Uromycladium maritimum, U . notabile, and U. 

 robinsoni. When the spermatia are associated with aecidia, it is only where 

 teleutospores and aecidia arise from the same mycelium that it can be 

 definitely stated that there are no uredospores. 



I n the second place, the characters of the spermogonium, such as posi- 

 tion, size, form, and colour, and its relative position to the accompanying 

 spore-forms, furnish characters for positive identification, although of 

 minor value. There is an interesting relation of the spermogonium to 

 other spore- forms to be noted in the cases afterwards referred to, where 

 there is a repeated formation of aecidiospores, uredospores, or teleuto- 

 spores, as the case may be, and these spore-forms do not directly proceed 

 to their normal development. In such cases, as far as our present know- 

 ledge goes, the spermogonioim is the only one which does not repeat itself, 

 as stated by Arthur 3 : "An observation more pertinent to our inquiry is that 

 the spermogonium occurs but once in the cycle, not being repeated with 

 each generation of repeating aecidia or uredo. In case the teleutospore 

 takes on the conidial function (repeating process), it is uncertain whether 

 the spermogonium is repeated with each summer generation or not. In 

 Puccinia malvaceamm and similar Lepto-Uredineae, the spermogonium 

 seems to be wholly suppressed even with the first generation in spring." 



The question of sexuality has been raised in connexion with the presence 

 of nuclei, but what constitutes an act of fertilization is interpreted differ- 

 ently by different authors. 



Sappin-Trouffy 2 , for instance, has observed in Uredineae having the 

 various stages the following nuclear cycle : 



Uni-nucleate. 



Mature teleutospores. 



Sporicliola. 



Mvn-lium. producing spermatia and aecidiospores. 



Spermatia. 



Bi-nucleate. 



Aecidiospores. 



Mycelium, producing uredo and teleutospores. 



Uredospores and 



Young teleutospores. 



in the mature teleutospore the two nuclei fuse, and this fusion was 



regarded by Sappin-Trouffy as an act of fertilization, but the fusion of 



s nuclei may be interpreted otherwise. Blackman 2 has confirmed the 



ove nuclear cycle, and concludes that the spermatia are male cells which 



have become functionless, the nuclear characters being those of male cells 



and not of spores. 



The fertile cell of the aecidium or primary aecidiospore becomes bi- 



leate by the nucleus of a neighbouring vegetative cell migrating through 



>e wall, and this association of the two nuclei Blackman considers to be 



Hindoo rather than the act of fusion in the teleutospore, since the fertile 



cell is stimulated to further development by the entrance of a nucleus from 



without. (Note 2, page 75.) 



