610 
Journal of Agricultural Research 
Vol. XXXI, No. 7 
Table IV .—Average measurements in microns of spores and asci of several strains 
of Sclerotinia libertiana as compared with each other and with S. intermedia, 
S. minor, and S. ricini —Continued 
S. INTERMEDIA 
Culture 
No. 
Host 
Asci 
Spores 
303 
Salsify........... .. 
7.5X127*0 
4.9X12. 7 
S. RICINI 
697 
1 Ricinus_____ __ __ 
8. 0X80-100 
4. 5X9-12 
S. MINOR 
1500 
Lettuce.________ __ 
8.9X141.0 
7.0X14.1 
Certain minor morphological variations of asci and spores are 
shown in Plate 3, A, a, b, c. These asci are each from a different 
strain of S. libertiana and they represent rather wide variations in 
size as well as in shape; but as more spores and asci were measured 
and studied the writer became more and more skeptical as to the 
importance of these variations. The stage of maturity of the 
apothecia and their variations in development due to the reactions 
to moisture, temperature, and light conditions are responsible for 
many changes in form and size of normal spores arid asci, even of 
the same strain, as well as such unusual forms as shown in Plate 
3, B, a , bj c , which came from the malformed apothecium shown in 
Plate 2, B. 
The apothecial measurements of several large sclerotial strains of 
Sclerotinia and of one strain of S. intermedia are included in Table 
III. The mature apothecia that were developed in good light 
usually attained a diameter of about 5 mm., but m exceptional cases 
some grew 10 to 13 mm. in diameter. The apothecia of S. inter - 
media , for the most part, range from 2 to 4 mm. in diameter. The 
average height of the apothecia above the surface of the sand in pot 
cultures was between 6 and 7 mm. Differences in depth at which 
the sclerotia were planted as well as fluctuations in light, are re¬ 
sponsible for so much variation in these dimensions that they can 
be considered only as indicative of the measurements that may 
ordinarily be expected. 
MICROCONIDIA 
Several groups of fungi, during some phase of their life history, 
develop sporelike bodies which on a morphological basis, might be 
called spores (pi. 4, H). Lack of definite knowledge concerning 
their functions, however, has caused considerable uncertainty as to 
the terminology to be used in speaking of these morphological units. 
In many ascomycetes these bodies are formed copiously by either in¬ 
tercalary or acrogenous abjunction and are called gonidia. They 
are often associated with ascocarps or other fruiting bodies and have 
been referred to as rudimentary spores. The spermatia of other 
fungi also seem to differ little if any from many acrogenously formed 
