579 
Life-history of Tetraclinis articulatci. 
Tetraclinis articulata is a tree forming forests of considerable extent 
in the mountains of Northern Africa, especially in Algeria and Morocco. 
The maximum height is given by Hooker and Ball (loc. cit.) as 30 feet, 
and by Engler (15) as 10 metres, but Dr. Moss informs me that the tree 
reaches a height of about 40 feet, half that height being typical of average 
trees. 
The material used in the present investigation was obtained from 
a single tree about 20 feet high, growing in the grounds of the South 
African Museum, Cape Town. I am glad to take this opportunity of 
thanking Dr. L. Peringuey, Director of the Museum, for his permission to 
collect the cones at frequent intervals. The origin of the tree in the South 
African Museum grounds is not certainly known, but it is believed to have 
been introduced there about 1840, along with a number of other exotic trees 
of similar age. 
The fixing fluids employed have been (i) Chromosmacetic acid, and 
(ii) Picric-corrosive sublimate-acetic. For certain stages the former 
proved most satisfactory, while in other cases the latter was decidedly 
superior. The methods employed in embedding, &c., have been the same 
as those used in the study of Actinostrobus (47). The triple stain has been 
used throughout, but for the cytological details of the meiotic divisions 
a duplicate series has been prepared with Heidenhain’s haematoxylin. 
The Microsporangiate Strobilus and Microsporogenesis. 
The male cones, before the final elongation which separates the sporo- 
phylls, are $-6 mm. long. The sporophylls, as in Widdringtonia (Saxton 
(44 and 45)), are more or less peltate and bear four microsporangia on the 
proximal side of the stalk. They are arranged in decussate pairs. The 
final elongation results in an increase of about 65 per cent, in length. The 
following are averages of measurements of well-grown cones : 
Length of cones before extension, 5*72 mm. 
Length of cones after extension, 9-43 mm. 
The microsporangia are exactly similar to those of other Cupressoi'deae. 
In the young sporangium there are three layers of cells outside the spore 
mother-cells, of which the outermost is the epidermis and persists as the 
mature wall, while the two inner are derived by the division of a single 
hypodermal layer which is part of the sporogenous tissue and which 
functions as a tapetum. 
In some ways the male cones of Tetraclinis have proved very well 
suited to a cytological investigation. A good range of stages is found in 
a single cone, and some variation in a single sporangium ; cones of the 
right age are very easily collected for a number of days, as they do not all 
develop simultaneously ; and cones of such an age are moderately easy to 
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