280 COMPARATIVE MORPHOLOGY OF FUNGI 



as here outlined occurs only under very favorable conditions. With the 

 sudden appearance of drought, development may be stopped at the stage 

 of Fig. 184, 1 or 2, and the observer would then find under the periderm 

 only a sterile sclerotial plectenchyma, possibly with the remains of the 

 conidial stage. The distinction between ectostroma and entostroma, 

 perhaps through greater resistance of the periderm or by unfavorable 

 growth conditions in the bark parenchyma, can be so disturbed that the 

 definite parts which form only perithecia or only conidia can no longer be 

 distinguished. Or the perithecia may arise under each other in several 

 layers. The figures given here represent only the simplest case. 



The second developmental series is characterized by the polysporous 

 asci and presents a type of development intermediate between that of 

 Diatrype and Eutypetla. The structure of the entostroma is that of the 

 Eutypella series, but the conidial stage is usually ectostromatic. It 

 may be conceived as beginning in forms like Quaternaria Persoonii, in 

 which the perithecia are in groups of two to four within the upper bark 

 tissues. The lower bark tissues and the surface of the wood are black- 

 ened. Entostromatic mycelium develops about the perithecial groups, 

 giving them a pustulate appearance. This mycelium often develops 

 over extensive areas, forming an effused, pustulate stroma, often bounded 

 beneath by a definite blackened zone. The stroma develops numerous 

 clusters of perithecia which are collectively erumpent through a small 

 ectostromatic disc. The grouping of the perithecia occurs before the 

 entostroma is differentiated, while it still forms effused patches (Weh- 

 meyer, 1923). This species shows a stromatic structure intermediate 

 between Eutypa and Eutypella, but with a conidial stage similar to that 

 of Diatrype. 



An unnamed species of Cryptovalsa on Cercis canadensis, reported 

 by Wehmeyer (1926), is a very primitive form. The perithecia, occurring 

 in pairs or singly, arise in the bark tissues but become partially or even 

 wholly sunken in the wood at maturity. Just above the perithecial 

 initials, there is a blackening of the bark tissues where some of the 

 hyphae penetrate the periderm and weaken it, thus enabling the growing 

 perithecial necks to penetrate. The blackened zone extends down to the 

 wood surface, where it spreads out between the perithecia. There is 

 very little entostromatic development and no ectostroma except the 

 blackened zone. Cryptovalsa sparsa is at about the stage of development 

 of Quaternaria Persoonii. 



In Cryptovalsa Nitschkei, the entostroma is more highly developed. 

 The entostromatic areas are usually effused and contain a number of 

 perithecial clusters, although isolated stromata occasionally occur with 

 only one group of perithecia. Ordinarily the ectostroma is little 

 developed, but in culture, they produced yellow, erumpent ectostromata 

 containing labyrinthiform locules bearing conidia. The entostromatic 



