76 LON A. HAWKINS 



well as swellings, and also definite outgrowths from one or both ends of 

 the spore. The latter (shown in figure 3) are of particular interest and 

 require some attention here. They are spherical in shape, dark brown or 

 black in color and appear in all respects similar to the chlamydospores or 

 appressoria which have been frequently described as resulting under certain 

 conditions, from the germination of spores of various Gloeosporium forms. 

 Appressoria have been described by Hasselbring 20 as forming when 

 nutrient materials are absent and when germinating spores or germ tubes 

 come in contact with such hard surfaces as are furnished by the cover 

 glass in a drop culture or by the epidermis of various fruits. This writer 

 considers that they function as holdfasts and that they result from a contact 

 stimulus acting upon spores or tubes which are not well nourished. That 

 such bodies are frequently formed when germ tubes come in contact with 

 the cover glass of a hanging drop culture, has often been demonstrated 

 in the present studies. They are especially characteristic of cultures with 

 certain salt solutions, at concentrations somewhat below that at which 



germination is entirely suppressed but above 

 that at which normal development occurs. Here 

 their formation does not appear to be related to 

 any contact stimulus, however. In some cases 



swollen bodies are produced which have the 

 Fig. 3. Germinating form Q appressoria but which are haline 

 spores from o. 00033^1 



Pb(NO ) X6so ^* e t " e usua l spores and germ-tubes of this 



.fungus, thus apparently differing from the 



appressoria only in not being brown or black in color. In the descriptions 

 which follow the term appressoria will be used to denote the dark colored, 

 appressorium-like bodies, and swellings of similar form but without dark 

 appearance will be termed hyaline appressoria. These terms are applied 

 here merely in a descriptive way, without intended implication that the 

 bodies thus designated may not be physiologically or otherwise different 

 from the appressoria of the mycologists. 



In concentrations of Pb(NO 3 ) 2 from o.oooim to 0.00005111, most of the 

 germination observed resulted in appressoria. Some of the similar, hyaline 

 swellings also occurred in these cultures. When cultures where appressoria 

 were common were allowed to remain in the thermostat for several days 

 and were examined from time to time, these swellings continued to develop 

 successively from the same spore, until sometimes as many as four 

 appeared together at one end (see fig. 4). In the formation of chains 

 of these bodies it appeared, from the observation of different stages, that 

 a second or later swelling may be brought about either by the germination 

 of one previously formed or by enlargement of the constricted portion of 



20 Hasselbring, H., The appressoria of anthracnoses. Bot. Gaz. 42: 135-142. 1906 



