60 DIVISION I. GENERAL MORPHOLOGI'. 



It is a universal histological law that every spore is the daughter of one or some- 

 times more than one mother-cell, which is consequently called the spore-mother-cell. 



There are many and great differences between spores and their mother-cells in 

 respect of their special qualities, structure, and mode of formation, and in respect of 

 their position in the life-history of the species and the homologies which result from it, 

 and several different kinds of spores may be formed in the course of development of a 

 single species* Hence there are several categories, kinds, or forms of spores and 

 spore-mother cells, that may be distinguished according to these different points of 

 view. In their terminology these distinctions are expressed sometimes by adjectives, 

 sometimes by compounds of the word spore, as swarm-spores, ascospores, &c., some- 

 times also by special words, gonidium, ascus, basidium, and others. Each of these 

 terms signifies a spore or its mother-cell in the general meaning of the word above 

 indicated, with a definite specific reference. A fuller explanation of the terms and 

 an account of the reasons for their adoption are reserved for Chapter IV. 



The distinction between spores and their mother-cells on the one hand and 

 vegetative cells on the other is naturally drawn first of all from cases in which the 

 differences are most distinctly marked, and these constitute the large majority. It is 

 to be expected that in a large and much graduated series of forms some would occur 

 in which those differences would be less marked, sometimes indeed be almost 

 obliterated. As examples of this may be mentioned the vegetative form described on 

 page 4 as Sprouting Fungus, in which each sprout may be quite rightly termed a spore 

 in the above acceptation of the word, and in the gemmae formed by the abjunction of 

 cells with the power of germination from the vegetative hyphae in the Mucorini, 

 Tremellineae, and Ascomycetes, which will be subsequently described. No confusion 

 would be caused by a consistent use of the word spore in these cases. Whether it 

 would be convenient that other terms should be introduced in its place is a matter to 

 be determined by judicious agreement in each case. 



Many of the peculiar characters of spores and many of the phenomena attending 

 their formation and ripening recur in the most different groups of the Fungi, and 

 would necessarily be included in a general survey. Others again are confined to 

 individual groups and can only be fully discussed with them. At the same time we 

 shall, I believe, get a clearer view of the whole subject if the second series of characters 

 is considered along with the first, and those points only are reserved for special 

 description in Division II which are quite irreconcilable with such general treatment ; 

 among these are especially questions concerning homologies and sexual relations 

 which are still in many respects obscure and debatable and must be considered in 

 each individual case. 



1. DEVELOPMENT AND SCATTERING OP SPORES. 



SECTION XV. According to our present views on the origin of cells, every cell is 

 the daughter of a mother-cell, and except in the cases of conjugation and rejuvenescence 

 is formed by a process of division which takes place in the mother-cell x . Either all 



1 I pass over for the present the conjugation and coalescence of cells for reasons of convenience 

 which have been partly intimated above ; this subject will be considered in Division II. Reju- 

 venescence I exclude because it is not the formation of a new cell, but only the transformation of a 

 previously existing cell. 



