MICROCERA. 33 



Xo. 6. A branch near Xo. 5 was neither inoculated, nor tied with cheese 

 cloth. On September 21, no spores of Microcera were to be found. On 

 September 28, no spores of Microcera were found. 



X"o. 7. A branch above Xo. 4 was neither inoculated, nor tied with 

 cheese cloth. When examined on September 28, no Microcera could be 

 found. 



During the first two weeks after these infection experiments were made 

 there were frequent rains, and the weather was quite moist. This was fol- 

 lowed by two weeks of drier weather during which the fungus apparently 

 ceased to grow. These inoculation experiments show that under favorable 

 climatic conditions like those under which they were carried on, the larvae 

 of Ale yr odes citri may readily be infected either directly from previously 

 infected larvae, or from pure cultures. 



GERMINATION OF CONIDIA. 



The conidia of Microcera germinated quite readily in water. On Octo- 

 ber 3, a hanging drop culture was made with conidia from a potato culture. 

 In 24 hours, one of the cells of the conidia, usually the end cell, sent out 

 hyphal tubes to a distance of one to four times the length of the conidia. 

 On the end of a number of these were seen small oval sporids (Fig. 19). 

 In 48 hours the hyphae were 6 to 7 times the length of the conidia, some 

 of them branched as in Fig. 19, and many sporids had formed. In six 

 days the branching hyphae were j\ ^r-^Z^ ^!k*" ' ' ' '-^^j-^ 



prominent, with many sporids. The /V^^"*^J> ^^v "*"^^?\ 



segments of the conidia had become if ^\ 



swollen, thus causing constrictions G?3 



Fig. 19. Conidium of Microcera germinating 



at the septa. and forming sporids. (a) Conidium. (?>) hyphal 



tube, (c) sporid, X 450. 



VARIATION IN SIZE OF CONIDIA. 



The measurements of conidia at various times and under various con- 

 ditions indicated a considerable variation in size. The greatest variation 

 was in the length. As has been said, the conidia varied from oval one- 

 celled spores to long lunate spores. Measurements of lunate spores on 

 larvae were as follows : 



On September 23, the first specimen from Sutherland after drying bore 

 conidia measuring 28 40 by 3.5 5 microns. On September 26, the second 

 lot of specimens from Sutherland, while still fresh, contained conidia meas- 

 uring 36 45X3.5 4.5 microns. On October 5, privet leaves from inocu- 

 lation experiment X^o. 4, at Gainesville, while still fresh, bore conidia meas- 

 uring 3152X3.5 4.5. 



Measurements of lunate spores in cultures were as follows: 



On September 17, conidia from cultures made September 14 measured 

 21 32X3.5 4.5 microns. On X T ovember 21, conidia from culture on 

 potato, measured 12 to 30 microns long; two-celled conidia were 12 microns, 

 the others longer. On February 2, 1908, from cultures 101 days old, made 

 October 26, 1907, on white cornmeal cultures not dried out; conidia in pink 



