Spermogonia and Spermatia. 



CHAPTER IV. 



SPERMOGONIA AND SPERMATIA. 



The spermogonium, sometimes called pycnidium, is a small punctiform 

 body, hemispherical to flask-shaped, produced beneath the epidermis or 

 cuticle, and ultimately the narrow neck bursts through in order to allow 

 the contents to escape into the air. The narrow opening is generally sur- 

 rounded by a brush of sterile projecting stiff hyphae, the so-called para- 

 physes, and in the interior of the spermogonium there are numerous con- 

 verging hyphae surmounted by very minute oval or rounded bodies borne 

 in short chains the so-called spermatia. These bodies were considered to 

 be of the nature of male sexual organs, hence the name; but whatever 

 may have been their original function, now lost in the course of develop- 

 ment, there is no reliable evidence to support the view of their being 

 sexual in function. 



The spermatia are embedded in a sugary secretion, and though it is 

 not known whether this serves to cause the spermatia to germinate, insects 

 are probably attracted to the spermogonia sometimes by means of this 

 sweet bait, and also by their powerful and penetrating odour, as in Puccinia 

 suaveolens Pers., which is so named on account of its sweet scent. The 

 honey colour of the spots may also serve as an attraction, and the project- 

 ing hairs or paraphyses are believed to retain the spermatia and prevent 

 them being washed away. 



Colour, scent, and honey dew will thus co-operate in alluring insects 

 to the spot, and the evident resemblance of these relations to those which 

 prevail in the fertilization of flowers by insects naturally led to the belief 

 of the spermogonia and spermatia being concerned in some way with 

 the fertilizing process. This view was further strengthened by the fact 

 that in Lichens, which possess similar structures, there called pycnidia, a 

 true process of fertilization occurs. But actual experiments fail to prove 

 any such connexion, and the probabilities are that the original function 

 has disappeared owing to modifications consequent upon' the fungus becom- 

 ing parasitic. Spermatia do not germinate in water, but do so when 

 placed in a suitable nutritive solution, such as white cane-sugar dissolved 

 in water. Germination consists in a minute prolongation at one end, which 

 ultimately becomes like the parent spore, and thus, as far as present know- 

 ledge goes, the spermatia are isolated structures, and do not enter into 

 the regular development of the fungus. 



Spermatia, whatever may be their function, do not occur as solitary 

 spore-forms, but always precede or accompany one of the others. They 

 are usually associated with aecidia, but this is not invariably the case, 

 for there may be aecidia without them, and in the absence of aecidia they 

 may be associated with other spore-forms, such as uredospores in the 

 case of Uromycladium robinsoni, Puccinia hieracii (Schum.) Mart. &c., and 

 teleutospores, as in P. liliacearum Duby and Uromycladium tepperianum 

 (Sacc.) McAlp., and either uredo or teleuto spores, as in U. maritimum. 

 The same mycelium which proceeds from (the teleutospores, and produces 

 the spermogonium, also produces aecidio uredo or teleutospores, as the 

 case may be, although it may seem a needless waste of material and an 

 unnecessary act, since the one is left behind in the race, while the others 



