844 Transactions of the Society. 



The plant under consideration also demonstrates some points 

 necessary for the completion of a theory of sexuality, which may be 

 stated as follows. 



Protoplasm contains two substances, the combined action of 

 which enables the plant to perform its vegetative functions, and 

 continue its existence as an individual ; the proof of this is the fact 

 that when the two components are differentiated into sexual organs, 

 neither of these alone can perform vegetative functions, which can 

 only be resumed after fertilization has effected a reunion of the 

 requisites. That a separation of vegetative protoplasm has taken 

 place is shown by reagents ; glycogen is absent from the basidia 

 (before fertilization) and cystidia of fungi, but is present in the 

 hyphae and spores; nuclein on the other hand is present in the 

 pollinodium of Milowia nivea and in the cystidia of all fungi 

 examined, but absent from every other part of the plant. In 

 Fucus vesieulosus and F. serratus the oospore behaves similarly to 

 the protoplasm of young parts of the thallus with reagents, but the 

 oosphere and antheridia differ from both and from each other. In 

 other experiments on plants belonging to widely separated families 

 the difference between the sexual and vegetative organs is equally 

 well marked, which, even when the significance from a chemical 

 point of view is not understood, clearly shows a difference of com- 

 position, the point of most importance to the present inquiry. 

 Tetragonidia, conidia, and the parthenogenetic reproductive bodies 

 of the Phseosjporese so far as examined give the same reactions as 

 the vegetative parts of the plants to which they belong. This 

 method when more fully developed and verified by extended 

 experiments, may prove of value in determining the sexual or 

 asexual nature of certain reproductive bodies belonging to the 

 lower plants respecting which, at present, opinions are divided. 

 As an example, no difference has been found in the protoplasm of 

 conjugating plants of Spirogyra ; and the mingling of vegetative 

 protoplasm to form a zygospore, in place of being considered a 

 sexual act, may be looked upon as the precursor of cross fertilization. 

 The advantage of this method over reproduction by conidia consists 

 in the zygospore being an admixture of two individuals, which pre- 

 sumably confers the same benefit as that effected by cross fertiliza- 

 tion in the higher plants; the disadvantage, compared with the 

 sexual method, which it shares with reproduction by fission, con- 

 sisting in the destruction of the parent plant, which survives when 

 parts only are specialized as reproductive organs. 



It has been already stated that in Miloivia, when the pollinodium 

 is not developed, the terminal cell, instead of developing into a 

 carpogonium, produces conidia; had this cell in such instances 

 developed into an organ resembling the carpogonium with its asci, 



