Pennsylvania for Sessions igoi-igoj. Ixxv 



Alay I. Dr. Miller, President, in the chair. Miss Marion 

 Mackenzie gave her monthly Phyto-phenological Report, 

 from which it appeared that the season was still an advanced 

 one for vegetation. A comparison of the flowering periods 

 of Dicentra cucullaria, Corniis florida, Viola pitbescens, etc., 

 showed that these and otlier species were from a week to ten 

 days ahead of their average blooming period. 



In continuation of the above report, Dr. Macfarlane tlien 

 spoke on "Recent Climatic Conditions in Relation to Plant 

 Life." He stated that owing to the early unfolding of 

 buds up to April 3d, the sudden frost of the evening of 

 April 4th-5th did considerable damage. The buds of 

 Ginkgo were more or less hurt, as were also those of Lilac, 

 but the plant that suffered most was Polygonum Sieboldii, 

 the shoots of which were quite destroyed where exposed to 

 full frost effects. The flower buds of Judas tree were in 

 many cases badly hurt. 



Dr. Henry Leffmann then spoke on "The Diatoms of 

 Agar-Agar." The Algal product Agar-Agar is a substance 

 of the fruit- jelly rather than the animal or nitrogenous- jelly 

 type. From its origin the commercial article seems pretty 

 often to contain diatoms, the commonest of which is Arach- 

 nodiscus Ehrenbergii, though Cocconeis is also represented. 

 The agar is secured along the Pacific coast where these 

 diatoms also occur. Since agar is now being used as thick- 

 ening jelly, the speaker believed that the occasional occur- 

 rence of the above diatoms might be an aid in detecting the 

 origin of the jelly. 



Dr. Macfarlane then spoke on "Parasitism in Plants 

 with Special Reference to that of the Mistletoe and Dod- 

 der." He said that some parasites showed no specific prefer- 

 ence in their food supply, and cited Comandra and Cassytha 

 as examples. Again in the case of Aphyllon, Epiphegns and 

 Conopholis, the parasite restricts its attack wholly to one 

 species or genus, and in such cases the parasitic degrada- 

 tion becomes increasingly marked and seed production more 



