[ 259 J 



XXIX. Extract from a Memoir on the Origin and Development of Vessels in Monocc- 

 tyledonous and Dicotyledonous Plants. By Dr. Francisco Ereire Allemao, of 

 Rio de Janeiro. Translated and communicated by John Miers, Esq., F.R.S., 

 F.L.S. Sfc. 



Read January 16th, 1855. 



IN 1849 I began a series of microscopical investigations upon several points of vegetable 

 anatomy, among which was one that attracted my chief attention, because of its greater 

 novelty, — the origin and development of vessels in the roots of plants. 



In 1851, I read before the Vellozian Society of Rio de Janeiro a short memoir, in 

 which the most important facts that I had observed were collected, and which appeared 

 to me wholly new to science; at least I have found no record of them in the books 

 within my reach. That memoir, being accompanied by drawings, could not then be 

 printed, but I afterwards revised it, made it somewhat shorter, added other remarks, and 

 suppressed the drawings : in this form it was published in the following year (1852), as 

 the "Third Memoir of my Botanical Exercises:" (Trabalhos da Sociedade Velloziana, 

 p. 101). 



In the year 1853 I continued the same pursuit, when my attention was not limited 

 to the examination of the growth of vessels in germinating seeds, but was directed also 

 to that of dicotyledonous plants considerably advanced towards a ligneous state : similar 

 observations, extended at the same time to the growth of monocotyledonous plants, 

 convinced me that their mode of development was exactly the same as in Dicotyledons. 



This last investigation is not yet completed; it will be of considerable length and 

 accompanied by explanatory drawings, so that I know not when it will be finished : but I 

 send you npw an extract from it, with such details as may be requisite to make the 

 drawings that accompany this understood : I am the more anxious to do this, in order to 

 learn whether my observations are new, and worthy of the attention of European botanists, 

 or whether they are already known or sufficiently exact. 



The Drawing A. shows the observations upon the growth of a young plant of Sida 

 carpinifolia. 



Eig. 1 (Tab. XXVII.) represents the plant of its natural size scarcely developed, showing 

 the epigeal cotyledons still enveloped in the seminal integuments. The caulicle (radicle) is 

 linear and without any ramifications, that is to say, without any radicular fibres yet formed. 



Eig. 2 shows the same plant much magnified, as observed under the microscope : the 

 cotyledons are thus seen with their nervures formed of tracheal vessels alone, of which 

 two constituting the midrib are continuous with those of the caulicle ; these are four in 

 number, distinct, entire, straight, parallel and equidistant, descending into the caulicle as 

 far as a : the lower portion of the caulicle does not yet exhibit any vessels, and the 

 radicular bulb, b, does not yet show any tendency to form roots. 



VOL. XXI. 2 M 



