Spore-Formation of Mesocarpece. ^e 



one and the same species {Moiigeoti'a calcarea, Clev.), the formation of 

 the spores may take place equally in the manner of the three above- 

 mentioned genera ; also that occasionally even the spores may be 

 formed without any conjugation, and further that in a plant found 

 growing last October in an aquatic stone house in the Upsala Botani- 

 cal Gardens, and which is described as Gonatonema ventricosum, the 

 spores are formed in a neutral way through the agency of cells never 

 intended for and incapable of conjugation. Such spores the author 

 calls agamospores, and he finds a second species of this new genus in 

 H assail 's anomalous Mesocarpus nofabih's. 



If the interpretation placed on the phenomena to be witnessed in 

 the Mesocarpeae by Prof. Pringsheim be accepted, then this family can 

 scarcely be left among the Conjugatae, and this would hold true also of 

 Wittrock's new genus, as indeed is so stated by himself. But may not 

 the phenomena be interpreted in yet one other way } First, as to the 

 agamospores in Gonatonema. Is it beyond the bounds of possibility 

 that, despite their external likeness to zygospores, these are simply 

 vegetative spores, to be compared to one of the so-called tetraspores 

 in Floridese } They surely cannot be compared to any form of or- 

 ganism itself the product of the commingling of the contents of two 

 different cells ! Another suggestion, to account for this agamospore, 

 has been made to me by my friend William Archer. It is that there 

 may have been a separation between the upper and lower portions of 

 the protoplasmic contents of the same cell, and that these, without 

 waiting for the formality of forming separate cells, may have then and 

 there conjugated. This is certainly a most ingenious suggestion, and 

 is stengthened by the well-known fact that, in some Desmids, after the 

 single-celled frond has divided into two halves, and before the newer 

 portions grow into anything like the similitude of the older por- 

 tions, the two halves, which were only just parted, will conjugate and 

 form an ordinary zygospore. De Bary gives some pretty figures of 

 this strange phenomenon, which, according to Mr. Archer, might be 

 carried one step further, and there be no parting at all. In favor of 

 my own idea I can only add that the first origin of what, in some of 

 the Florideae, will form the tetraspores, and the origin of these agamo- 

 spores, appear to me to be the same. Next as to the sporocarps in 

 Mesocarpus. The difterentiation into sexual entities of the protoplas- 

 mic contents of cells is confessedly, at first, scarcely perceptible. It 

 would be impossible, in many cases, to say with any confidence, this one 

 is the germ cell, and that one is the sperm cell. But gradually a differ- 

 entiation appears in that the contents of the former exhibit themselves 

 as passive, and of the latter as active ; the contents of the one re- 

 main quiescent, those of the other pass over to conjugate with the for- 

 mer, but all through the contents that commingle are almost in every 

 case alike' in quantity. Carry the differentiation a step further on, and 



