ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 195 



tion of the common ground-parenchyma, arising at the non-stratified 



apex, which becomes enclosed distally by fusion of the procambial strands, 

 and hence differs in no respect from the external " cortical " parenchyma. 

 Tlie suggestion is put forward that all ideas of "monostely" and 

 "polystely," and of "medulla " and " cortex " as separate morphological 

 entities, are based on an artificial conception of the structures involved. 

 Anatomy of Anemiopsis californica.* — T. Holm gives an account 

 of the anatomy of the vegetative organs of this plant — a member of the 

 tribe Saururese of the order Piperaceae— included by Bentham and 

 Hooker in Houttuynia, but considered as a distinct genus by Eichler, 

 De Candolle, and others. The plant lives in moist, saline localities, and 

 may perhaps be regarded as a halophyte. The author considers, how- 

 ever, that its structure may be defined more properly as simply pipera- 

 ceoua than either halophilous or xerophilous. The most conspicuous 

 characters — the prominently developed hypoderm and the abundance of 

 secreting cells throughout the various tissues — are in conformity with 

 the general structure of the order rather than with halophytes. 

 There are also points of difference in the anatomy of the leaves, petiole 

 and stem. It would appear as if Anemiopsis, so far as concerns its 

 structure, gives a better illustration of one of the several types of the 

 Piperaceee than of any specialised type modified in accordance with the 

 environment. 



Stomata of Holacantha.f — C E. Bessey describes the stomatal 

 apparatus of the burro thorn (Holacantha Emoryi), a leafless, thorny 

 shrub about 3 metres high (or sometimes arborescent), which forms 

 impenetrable thickets in the deserts of the Southern States. It is a 

 member of the Simarubese. The surface of the branches and thorns (or 

 modified branches) is pea-green in colour. The epidermis is 3—5 layers 

 deep, with a remarkably thick outer wall and much thickened lateral walls. 

 Below the epidermis is a thick mass of palisade cells. The stomata are 

 thickly scattered over the surface, numbering about 73 per sq. mm. Each 

 lies at the bottom of a narrow chimney-shaped cavity, which passes 

 entirely through the thickness of the epidermis and is prolonged both 

 above and below it ; the cavity is of a somewhat smaller diameter at the 

 mouth. The stomal apparatus at the lower end of the chimney consists 

 of from 40-GO cells, which extend down into the mass of palisade tissue. 

 It is almost circular in cross section, and consists of from 10-12 rows 

 of thinner-walled cells than those forming the main part of the chimney. 

 At the bottom of this structure is the proper stoma, which closely 

 resembles that of ordinary plants, and beneath it is the usual air-cavity. 

 The whole forms a successful means for protecting the plant against 

 loss of water while allowing, free access of carbon-dioxide. The highly 

 transparent epidermis permits photosynthesis. 



Reproductive. 



Pro-embryo of the Bennettitese.J — Gr. R. Wieland describes pro- 

 embryos which he has seen in fruits of Cycadeoidea from the Black Hills. 



* Amer. Journ. Sci., ser. 4. xix. (1905) pp. 76-82 (fig. in text). 



t Bull. Torrey Bot. Club, xxxi. (1904) pp. 52:1-7. 



X Amer. Journ. Sci.. ser. 4, xviii. (1904) pp. 445-7 (1 pi.). 



