76 The President's Address. 



observes that " the distribution of the veins in Umbelliferee 

 is very variable in different species, but constant and highly- 

 characteristic in each species :" " that many of the leaves of 

 this order have a venation like that of other leaves, and may 

 be classified with them ; but that a considerable number have 

 a kind of venation peculiar to themselves, which does not 

 find a place under any of the divisions that have heretofore 

 existed :" " that this peculiarity consists in the existence of 

 a vein at the very edge of the leaf itself, and which more or 

 less entirely fringes the whole margin." This venation he 

 finds in one half if not m(?re of the UmbelliferEe. 



In December Mr. Tatem described new species of micro- 

 scopic animals belonging to the genera Epistylis and Caeno- 

 morpha. 



Two other papers of the session relate to microscopic 

 organisms : the first by Mr. Sheppard, communicated by the 

 Rev. J. B. Reade, who previously had investigated the sub- 

 ject. This paper, " On the Production of Colour by Micro- 

 scopic Organisms," brought a subject before us interesting 

 in itself and new to English observers. Dr. Cohn of Breslau 

 had, however, made similar researches, which are recorded 

 in our ' Journal ' for last July, and in a letter to Mr. Shep- 

 pard, dated Breslau, Nov. 1, 186T, which I read at a recent 

 Council meeting. Dr. Cohn says, " Curiously enough in the 

 last summer a 'third memoir about * Phycocyan ' (his own 

 name for the colouring material) has appeared in the 

 ' Botanische Zeitung von Mohl und De Bary,' from Dr. 

 Aschkenasi, each observation quite independently made from 

 the others." 



We may therefore hope that the question, " Whence the 

 colour ?" will be soon and fully answered. Mr. Sheppard is 

 of opinion that the intense colour produced in a few hours 

 by a few grains of almost colourless organisms, in more than 

 two ounces of albuminous fluid, is due to the action of life 

 on this suitable vehicle; and he supports his opinion by a 

 reference to M. Pasteur's statement on the similar action of 

 certain monads and vibrios on nitrogenous substances. 



Dr. Cohn, on the other hand, is of opinion that his Phy- 

 cocyan already exists along Avith Chlorophyll in the cells of 

 these low organisms, and " on the death of the cells the phy- 

 cocyan is dissolved in the water, which penetrates by endos- 

 mosis, and then appears by dialysis as a blue fluid, whilst 

 the chlorophyll remains in the cells." (' Journal,' p. J309.) 



But Dr. Cohn, in thanking Mr. Sheppaid " for his highly 

 interesting communication," admits the necessity of further 

 experiments J, " that the truth may be established ;" and after 



