312 Miscellaneous. 



One morning in the month of July, about 5 o'clock, in the Botanic 

 Garden of Venice, two plants of Mimosa pudica, kept in a conserva- 

 tory (perfectly expanded), presented an aspect of luxuriant vegeta- 

 tion. Another, exposed in the open air, had its leaves entirely closed 

 and the stems bent. A fourth, placed in another part of the garden, 

 was half-closed ; and another, in a separate place, was quite closed. 

 On the day preceding, the gardener had, at my orders, shut up the 

 last in a dark place three hours before sunrise. 



I took care also to verify the influence exerted upon the Mimosa 

 by the artificial light of a lamp, and I found the growth was from 

 3 to 5 centimetres. — La Lumiere, July 17, 1858. 



General Examination of the Group Euphorbiaceae. 

 By M. H. Baillon. 



The great number of facts met with in the study of about fifteen 

 hundred species, cultivated at Paris or preserved in the collections, 

 have compelled the author to divide into two series his ' Etude gene- 

 rale du groupe des Euphorbiacees.' In the first part he combines 

 the matters relating to the search for types, the natural affinities, 

 classification, descriptions of genera, and organography, based as far 

 as possible upon organogenic studies. 



It is only in the adult state that the existence of compound leaves 

 can be regarded as exceptional in this order. Very frequently they 

 are compound at their first appearance ; but the terminal lobe only 

 becomes developed, the lateral being abortive. They then become 

 lamellae of variable form, and very often true glands, which occupy 

 the base of the blade. It is simply by such an arrest of development 

 that a Cremophyllum differs from a Balechampia ; but the two genera 

 cannot be otherwise separated. There are also often lobes of abortive 

 leaves, destitute of parenchyma, and reduced to their nervures ter- 

 minating in a glandular thickening, which have been regarded as 

 branched hairs. 



The structure of the male flower presents every possible modifica- 

 tion, from the diplostemonous type of the andrcecium to the indefinite 

 arrangement of a variable number of naked stamens. Consequently, 

 the only fixed characters that can be resorted to in the Euphorbiaceae 

 lie in the female flower, and, in this, in the gynaecium. 



Hence the extent of the researches relating to this organ. Its 

 development has been followed in all the plants cultivated in the 

 Paris gardens and hot-houses, from the appearance of the carpellary 

 leaves upon a common, central, isolated axis, up to the time when 

 the ovules developed higher up on the same axis have acquired their 

 double integuments. 



It is the outer integument that forms the caruncle of the Euphor- 

 biaceae, by a thickening of the exostome, and this in a constant 

 manner. Its origin can no longer be attributed to the cellular cap 

 which arises from the placenta and advances to meet the ovule. 

 There is always a period when these two structures are completely 

 independent, and their perfect contact takes place at the time when 



