CHAPTER III. SPORES OF FUNGI. 



of which those named Cladosporium herbarum, Dematium 

 are the best known ; to these may be added the delicate 

 botryosporum 2 and many others. 



Connected with these three kinds of acrogenous 

 abjunction of spores is one which is less distinctly 

 marked and which may be termed the mode of cross- 

 septation (Querzergliederung). In this the terminal por- 

 tion of a hypha or hyphal branch grows first of all to 

 a certain length, and then ceases to elongate but is divided 

 by cross septa into a number of spore-cells. 



This mode of formation is seen most distinctly in 

 the sporogenous branches of strong specimens of Oidium 

 lactis 3 which rise into the air above the substratum. 

 These branches have a cylindrical form and are many 

 times longer than broad. When they have ceased to 

 elongate they quickly divide by formation of cross septa 

 into numerous cylindrical spores which are from one to 

 two times longer than broad. In small specimens this 

 cross-septation may extend over the whole plant, occur- 

 ring even in the branches of the mycelium in the 

 substratum. The formation of cross septa appears to 

 commence in stronger individuals at the free apical 

 extremity and to advance basipetally; but this point 

 is quite as uncertain as the question, whether the sporo- 

 genous branch consists at first of a number of longer 

 cells which are afterwards divided into the short members 

 by repeated intercalary bipartition, or whether the latter 

 are the first divisions formed either simultaneously or 

 successively and in basipetal order in the branch which 

 was up to the time of their formation unicellular; on 

 these points further examination of the branches of 

 this Oidium is to be desired. Of similar character are 

 the gonidial mother-cells of Syncephalis and Piptoce- 

 phalis 4 , which spring simultaneously from the apex of 

 the capitate extremities (basidia) of the sporophores and 

 form a small clustered head. They have the form of 

 elongated cylinders with rounded apices, and are divided 

 after they have ceased to grow in length into several 

 short cylindrical spores by transverse septa formed either 

 sively and in basipetal order, but always very rapidly. 



herbarum 1 and Alternaria 

 heads of Myriocephalum 



FIG. 34. Species of Alternaria. a 

 and * extremities of a sporiferous 

 hypha growing obliquely into the air 

 from a specimen grown on a microscopic 

 slide, a on the 4th Aug. at midday, A some 

 23 hours later ; the two rows of spores 

 which are still simple in a are branched 

 in b. c a young sporophore on a my- 

 celial filament submerged in water. The 

 membranes of the pointed ovoid spores 

 are yellowish brown where they show 

 partition-walls in their interior and are 

 colourless only at the upper pointed 

 extremities. This is the case also with 

 the youngest and still small spores, the 

 sporophores and the mycelium, a and * 

 magn. about 145, c 225 times. 



simultaneously or succes- 



1 Low in Pringsheim's Jahrb. VI, p. 494. Penicillium cladosporioides, P. viride, P. chlorinurn, all 

 of Fresenius (Beitr.), and P. olivaceum, Corda, are evidently the same form. Even if Tulasne's view 

 that the plant belongs to Pleospora herbarum is not confirmed, its connection with one of the allied 

 Sphaeriaceae is more than probable. 2 Fresenius, Beitr. t. V. 



3 Fresenius, Beitr. Brefeld, Ueber Gahrung in Thiel's Landw. Jahrb. V, 1876, t. II. 



4 De Bary und Woronin, Beitr. II. Brefeld, Schimmelpilze, I. Van Tieghem et Le Monnier in 

 Ann. d. Sc. nat. Sen 5, XVII, p. 370. See also below, sect. XLIII, Fig. 74. 



F 2 



