DIMORPHISM IN FUNGI. 137 



the time they were sown until the experiment was concluded. All 

 those infected with barberry fungus gave rise to the Undo, whilst 

 none of the check plants developed the disease. Of half-a-dozen 

 small barberry plants three were infected with the pro-mycelium 

 spores of Puccinia graminis from wheat, the other three being 

 kept as check plants. The three infected plants produced 

 Vadium; the three control plants remained perfectly free from 

 y£cidium. Besides the cluster cups there exists in company with 

 the yEcidium another set of organs developed from the same 

 mycelium, called spermogonia. They are small, flask-shaped 

 bodies, sunk in the substance of the leaf, on the opposite side of 

 the leaf to the yEcidiiun, and they are filled with delicate threads, 

 which bear upon their ends chains of minute bodies called sper- 

 matia. There is little doubt that they play the part of the male 

 element, and are the small bodies constantly seen surrounding 

 and adhering to the spores of yEcidium. 



According to this view, then, we have no less than five kinds 

 of reproductive forms in connection with this fungus, viz. — 

 yEcidium, Spermogonia, Uredo, Puccinia, and Pro-mycelium. It 

 should also be said that while ^"Ecidium berberidis is supposed to 

 be the y£cidium in connection with the summer mildew, P. 

 graminis; Aicidium asperifolii, an ^'Eciditi/n belonging to the 

 Borage family, is supposed to be the form connected with the 

 spring mildew, F. rubigo-vera. Mr. Worthington Smith objects to 

 these conclusions on the following grounds :— That corn is so 

 seldom free from red rust, and barberry bushes so seldom free 

 from barberry blight, that there is never any certainty that both 

 corn and barberry bush do not possess traces of the disease before 

 the experiments are commenced. And that as pro-mycelium, 

 pro-myceUum spores, and sporidioles are potential, both in Puc- 

 cinia and j^cidium alike, it is unlikely that there is any genetic 

 connection between these fungi. He traverses an argument from 

 analogy, advanced by some believers in heteroecism, viz. — the 

 change of host in certain entozoa, which is too. long for us to 

 enter into in these pages. He complains that Mr. Plowright has 

 not given an illustration of his own of the germ-tube of the pro- 

 mycelium spore piercing the epidermal cells of a barberry leaf, 

 and as to the ^-Ecidiuiii of the Spring Rust, .-Ecidiiun asperifolii, he 



