REPORT OP COMMITTEE ox PUBLICATION 139 



exposed to strong sunlight but so far as could be observed the germination 

 was as rapid as in the case of spores placed in an ice-box. Furthermore, 

 conidia have been placed in a drop of water suspended from the cover of a 

 Van Tiegham cell and the culture placed on the stage of the microscope, 

 for continuous observation. In this case a strong light continually passes 

 through the culture. By this method of procedure germination has been 

 obtained in one-half to one hour. In our opinion the failure to germinate, 

 apparently caused by strong light, may be due rather to a higher tempera- 

 ture. Indeed, Farlow (1876) states that the direct rays of the sun heats the 

 water causing such rapid evaporation that germination could not occur. 



According to Istvanffi (1913) a certain proportion of the conidia which 

 do not germinate are still immature even though they may be of full-size. He 

 says . . . (free translation) "the conidia in which karykinesis is already 

 completed are not necessarily mature even though they have attained their 

 full size. We have observed that the conidium still undergoes certain trans- 

 formations if they are maintained in a moist atmosphere, namely, that the 

 plasma becomes more reticulated in structure. These changes occupy 

 about three or four hours. During this period the vacuoles become larger 

 . . . and if examined in water the plasma appears granular." 



It is certain that one who has studied conidial germination for some 

 time will be able to state readily and with a fair degree of certainty, which 

 conidia will not germinate. To describe this distinction is difficult but in 

 general it may be said to be that the protoplasm of immature conidia appears 

 more finely granular, denser and to have a much deeper greenish color. 

 Before germination the protoplasm becomes more hyalin and less dense 

 probably due to the appearance of the numerous vacuoles, noted by 

 Istvanffi. 



On the other hand the conidia may be too old to germinate, as has been 

 pointed out previously by the writer (1913). Such conidia are characterized 

 by the coarsely granular, brown protoplasm. 



A third type of conidia, to which Istvanffi takes exception, has also been 

 described by the writer, as "partly or wholly filled with a highly refractive 

 drop which appears to be oleaginous in nature". Istvanffi admits that a 

 conidium treated with osmic acid becomes a deep brown indicating the pos- 

 sible presence of some oily substance but he claims that the oil is present 

 as minute drops. In this same connection both Viala (1893) and Patrigeon 

 (1887) state that there are numerous brilliant or refringent drops present in 

 the conidium. At the same time, Istvanffi states that the supposed error may 

 be due to the fact that vacuoles are very abundant in the conidium and that 

 these, being clear, "may resemble the ordinary refringence of the drops of 

 oil." It will be noted that the writer stated that these refringent bodies 

 remain in the conidium after germination. If vacuoles had been mistaken 

 for independent bodies in the protoplasm, would they remain as such in an 

 empty conidium? There is no question that in some cases, a clear, highly 

 refringent, and well-defined body or "drop" remains in the conidium after 

 germination. Its exact composition has not been determined but the possi- 

 bilities are either oil or glycogen. 



The vitality of the conidia varies with the conditions of humidity and 

 temperature. Istvanffi states that at a temperature of 8 to 10 C. they 

 will retain their vitality for two or three weeks and if placed directly upon 



