FORMATION OF CELLS. 



II 



with the former; and from this the reconstruction of a cell results. Here, as with 

 the conjugation of the Gonjugatae and some Fungi, the cell which results in this 

 manner from the coalescence is always a reproductive cell ; with it begins the 

 formation of a new individual plant. In fertilisation one of the two bodies is evidently- 

 very different from the other ; it may therefore be assumed that in conjugation also 

 a difference exists, although at present undiscovered, between the coalescing cells. 



C. Free Cell-formation. — In the pro- 

 toplasmic body of a cell new centres of 

 formation arise, around each of which a 

 portion of the protoplasm gathers, and 

 forms a cell. Another portion of the proto- 

 plasm rema'ms o'ver, and represents the still- 

 persisting protoplasmic body of the mother- 

 cell, which survives for a longer or shorter 

 time. The new centres of formation may 

 or may not be indicated by the previous 

 appearance of nuclei. Generally, the num- 

 ber of daughter-cells which arise in this 

 manner is considerable ; as an instance may 

 be mentioned the formation of spores in 

 a small Ascomycete, a Peziza^ (Fig- 7)- 

 The sac-like mother-cells of the spores 

 {a) are at first densely filled with pro- 

 toplasm, and contain only one small 

 nucleus. This disappears ; /. e. its sub- 

 stance becomes distributed through that 

 of the protoplasm ; this latter becomes 

 frothy, and roundish drops of sap make 

 their appearance in it {b, c'). Preparation 

 is made for the formation of spores by 

 the condensation of the protoplasm in the 

 upper part of the sac, while in the lower 

 part it remains frothy {e, /). The forma- 

 tion of spores does not in this case precede 

 the appearance of the nuclei ; and the 

 spores always remain devoid of a nucleus ; 

 and this is the more instructive as in other 

 Pezizae {e. g. P. confluens^ according to De 

 Bary) nuclei are formed in the first place, 

 around each of which a lump of protoplasm 

 collects-, which then forms the spore. In 

 this case eight spores are always formed 

 in each sac within the upper dense proto- 

 plasm ; /. e. around each of eight points a 

 portion of the protoplasm collects in an 

 ellipsoidal mass (^) ; each such collection 

 consists at first of coarse-grained protoplasm surrounded by a clear space ; a portion of 



Fig. T.—Peziza convexula. A vertical section of the whole 

 plant { X about 20) ; h hymenium, i. e. the layer in which the spore- 

 forming sacs lie ; 5 the tissue of the Fungus enveloping the 

 hymenium at its edge 4^ in a cup-like manner; at the base of 

 the tissue 5 fine threads arise, which grow between the particles 

 of earth. B a smaller portion of the hymenium (x 550) ; sh sub- 

 hymenial layer of densely interwoven cell-filaments (hyphae); 

 a—f spore-forming sacs ; among them thinner sacs, the. para- 

 physes, in which lie red granules. 



^ It appears in considerable quantity on the ground among Phascum along forest-paths in the 

 neighbourhood of Bonn in the month of March. The cup is from |-i inch broad, brick-red, sessile, 

 with slightly projecting rim. According to Rabenhorst, Deutschlands Kryptogamenflora, 1844, p. 368, 

 it may be P. convexula. 



^ In the embryo-sac of Phanerogams fresh nuclei are formed in the protoplasm, and around 

 each of these one cell. (Cf. Book II. Conifers, Monocotyledons, Dicotyledons.) 



