148 



on a corn-meal agar plate and allowed 24 hours to grow, by which time a 

 vigorous mycelium had developed. A goodly quantity of conidia of H. 

 No. 1 was then placed in the midst of this young but well-established M8 

 colony, but it remained uniform to full occupation of the plate^hpwing no 

 saltations. 



Implanting conidia of H. No. 1 in a partly developed colony of the samz 

 strain. This experiment was conducted like that of wounding except that 

 instead of using the hot wire conidia of H. No. 1 were implanted at the 

 points indicated in PI. XXIX, below. All implants within the colony 

 grew sparingly and resulted in small clumps 1 2 mm. in diameter and 

 highly sporiferous (PI. XXX, above). Implants at the edge grew poorly, 

 but those a few millimeters outside the colony became established and grew 

 well, each implant developing as an independent colony and inhibiting ad- 

 vancement of the old colony, but bearing no resemblance to a saltant. 

 In one case, however, such implants showed marked change in characters 

 and are still under culture as saltants (M70, PI. XXX, upper fig.), though 

 efforts to produce other saltants in this manner were fruitless. 



Implanting other Helminthosporiums. In a way similar to that of the 

 last experiment numerous other species or saltants (e.g. H. No. 2 and M6) 

 were implanted in an H. No. 1 colony, and always with the result that the 

 implant either failed utterly to establish itself or developed as an entirely 

 independent colony that did not blend with the main colony, being in this 

 unlike a saltant sector in character. If implants were put about 3 mm. be- 

 yond the tips of the advancing mycelium, the conidia were observed to 

 germinate before the mycelium of the H. No. 1 colony arrived, but even 

 such implants became entirely submerged and lost. 



Two entirely distinct types of Helminthosporium, found intermingled 

 on a single grain of wheat, were planted together an oese of suspen- 

 sion of the mixed conidia on an agar plate. The resulting colonies gave 

 the two types of Helminthosporium, but did not give the sectors so char- 

 acteristic of saltants. 



Saltation not due to parasites. The saltant sectors and their transfers 

 often differed so strikingly from their originals, particularly when they bore 

 few conidia and had much white aerial mycelium (see PI. XXVII) 

 as to suggest that perhaps the great difference w r as due to a parasite 

 growing in the Helminthosporium colony. Close microscopic inspection 

 of saltant sectors showed that there was only one type of mycelium present, 

 that it was all indistinguishable from Helminthosporium mycelium, and 



