MONOOItAI'U OF THE LAIiOULBENI ACK.i; 



203 



Amorphomyces they are continuous (Plate V, fig. 20), in all others they are divided 

 into two cells by a septum or psoudoseptum. In the great majority of cases the two 

 spore segments are of unequal size ; that which is terminal in relation to the axis of 

 growth being, as a rule, much the longest: although in a few cases, as in Zodiomyces 

 and Ceratomyees (Plates XXIV to XXVI), the reverse is true ; while in still other 

 instances the septum may be more nearly median, as in Compsomyces (Plate XI, fig. 

 15). The spore contents usually consists of more or less homogeneous granular pro- 

 toplasm, except in the genus Ainorphomyces, the spores of which when living contain 

 numerous, often large, oil globules. In all cases a large spherical nucleus may be. as 

 a rule, readily demonstrated in either segment (Plate I, hg. 13). A gelatinous enve- 

 lope, more or less well developed and characteristically thickened about its base, 

 always surrounds the spore ; serving as a protective covering for the latter as well as 

 facilitating its adherence to the host insect when it comes in contact with its surface. 

 In the majority of cases this envelope, though often adherent about the tip of the spore, 

 is continuous around it; but in Ceratomyees furcatns and C. contortus (Plate XXV, figs. 4 

 and 10) the separation between the spore segments involves the envelope also, which 

 is marked by a corresponding constriction. 



The spores are produced in the asci in fours or eights (Plate XXIV, fig. 9, Plate 

 XI, fig. 17), in the first instance usually disposed more or less definitely in pairs, one 

 of which is slightly higher than the other ; and the members of a given spore pair are 

 discharged together through the pore of the perithecium, the ascus wall having been 

 previously absorbed. The juxtaposition of two individuals at the point of contact 

 with the host, a condition essential for the perpetuation of the dioecious species, is 

 thus insured in a majority of cases (Plate III, fig. 5). The spores are formed in the 

 ascus, and therefore lie in the cavity of the perithecium after the wall of the latter 

 has been absorbed, with the basal half uppermost; and the base is therefore directed 

 towards the substratum on which it is discharged. Having become attached to a 

 proper host, the swollen portion about the base, by its peculiar form, assists the spore 

 in assuming the position necessary for germination; the upper extremity, if at first 

 adherent, soon freeing itself and projecting from the substratum at an acute angle. 

 A conspicuous exception to the conditions just described is found in the genus Mos- 

 chomyces, the minute spores of which are irregularly distichous in the eight-spored 

 ascus, and become free in a mass within the distal portion of the perithecium, whence 

 they are discharged, not in pairs but in small masses, each mass probably giving rise 

 to the so-called individual, which may thus in reality be compound (Plate XI, figs. 16 

 and 18). 



