258 The Ohio Journal of Science [Vol. XVI, No. 7, 



if any wood fibres. This variation is undoubtedly related to 

 the degree of differentiation attained before the advent of the 

 mites in the spring growth period. 



The hyperplasia of the cortex of the branch base is a con- 

 stant character. The stone cells are found aggregated into 

 sub-spherical masses, a condition also true of the crystal 

 bearing cells. These masses were much larger and more num- 

 erous than those found in the normal nodes, and often are 

 found in juxtaposition (PI. XIII, Fig. 1 c). 



The cork developes a greater thickness than normally, but 

 is not sharply defined from the primary cortical parenchyma. 

 The elements of this latter tissue do not thicken their walls. 



The above study is corroborative of Kiister's (15) dictum 

 that all witches-brooms, whether mite or fungus induced, 

 exhibit an essentially undifferentiated condition. 



Kellerman and Swingle (12, 13) have associated a fungus 

 (Sphaerotheca phytoptophila Kell. and Sw.) with this gall. 

 No mycelium was seen in the affected tissues; indeed none 

 would be expected belonging to the fungus named, since its 

 position among the Erysiphaceas would indicate it to be wholly 

 superficial, the haustoria only affecting epidermal cells. Other 

 well known witches-brooms, particularly those of Europe, 

 have been shown to be caused by mites only. One on Syringa 

 is especially striking. See Abromeit (1). There can be no 

 doubt that the kataplasma under discussion, is wholly induced 

 through the agency of acarinous organisms. 



Lepidoptera. 



Practically all of the lepidopterous galls are of the stem 

 kataplasma type. The larva works its way into the center of 

 the stem and from that vantage point brings about important 

 deviations from the normal sequence of events in the growth of 

 the tissue. This is in marked contrast to the mite induced galls, 

 for the mites occupy at first at least, an external position. 

 Stem mite galls are known, however, which at length enclose 

 the animals. 



2. Lepidopteron (species undetermined). This gall, (PI. 

 XIX, Fig. 2) is an aborted shoot from a lateral bud, developing 

 very rapidly in the early spring, reaching its full size (in Kansas) 

 toward the end of April. 1^2 ~ 3 cm. long, 4-6 mm. wide. 

 The nodes near the end of the gall bear small leaves which die 



