464 PROCEEDINGS OF THE ACADEMY OP [1881. 



growers especiall}' had found it to interfere seriously with their 

 profits. The injury was caused b}^ the projection of the sporangia 

 which covered the flowers and leaves of the roses as if profusely 

 dusted with black pepper. Tlie flowex's were almost unsaleable as 

 the first impression was that the black dots were Aphides. 



Mr, J. B. Ellis, of Newfield, N. J., to whom he was indebted for 

 the identification of the species, had informed him that it was 

 somewhat rare in that vicinity. In the greenhouses referred to 

 they were in immense profusion, the conditions of growth being 

 probably more favorable. Mr. Meehan described the growth of 

 the plant and the behavior of the asci in the generation and expul- 

 sion of the sporangia, which corroborated the facts detailed in 

 the memoir of Eugene Coemans, published in 18.59 in the Bulletin 

 of the Royal Academy of Sciences of Brussels. M. Coemans 

 found the plant on half-dried cow-droppings, in August, and in 

 these greenhouse cases it was also growing in half-i'otten cow- 

 manure used for enriching the soil. Mr. Ellis reports that it is 

 sometimes found on other manures, and so may be less rare than 

 supposed. The projection of the sporangia has been noted by 

 European observers, and originated Fore's name Pilobolus, literally 

 the hat- or cap-thrower. The sporangia appear as small black 

 caps on the top of the cr3^stal-like asci, and are expelled with great 

 force. By careful measurements they were found to be thrown 

 when the direction was perpendicular, to a height of four feet. 

 Coemans does not seem satisfied that the exact process has been 

 made clear by which this remarkable projection is eflfected. It 

 has been supposed that carbonic acid gas is generated, which, 

 distending the cysts, causes them at length to burst at the thinnest 

 part, which is the apex, and the sporangia are then blown out by 

 the gas, as would be a cork from a bottle of champagne. Again 

 Coemans finds a double membrane to the asci, and believes that 

 by the agency of light the inner membrane contracts in a different 

 manner to the outer, and that the projection is the result of this 

 peculiar contraction. Mr. Meehan observed that the sporangia 

 were expelled from the interior of the asci before they were finally 

 discharged, and that they were always projected in a direct line 

 from the centre, which would hardly be the case if a mere explo- 

 sion of gas directed the movement. One large rose-grower had 

 found, that sprinkling the surface of the earth under the rose 

 plants with about the eighth of an inch of dry earth, effectually 

 allayed the projectile annoyance. 



December 20. 

 The President, Dr. Ruschenberger, in the chair. 

 Twenty-five persons present. 



The deaths of Edw. Taylor and Dr. Isaac I. Haj^es, members, 

 were announced. 



