ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 649 



discusses at great length the various theories as to the homology of 

 the ovule and of its parts ; and finally adduces arguments in favour 

 of his previously published view that the ovule is homologous to a 

 pinna or section of a leaf (foliolum). The ordinary position of the 

 nucellus in the ovule is at first terminal ; and it sometimes also 

 occupies this position in monstrosities, especially when the ovular 

 leaflet does not assume a distinctly foliar character. But when 

 phyllody is strongly manifested, it is seen that the nucellus is not 

 the true apex of the foliar leaflet, having a superficial lateral position. 

 The morphological value of the nucellus is not affected by the 

 question whether it originally occupies or only subsequently assumes 

 a lateral position. 



Phytoblasts and their Pseudopodia.* — According to Prof. H. 

 Baillon every vegetable or vegetable organism commences its existence 

 as a phytoblast, the life of which may go through distinct periods, 

 and which may have various degrees of complexity of structure. The 

 phytoblast is of an albuminoid nature, like the lowest animals ; and 

 its reactions are proteid. Like truly animal substances, it is attacked 

 by ammonia and by other special reagents ; and behaves in every 

 respect like animal sarcode. With its movements are associated 

 pseudopodia, produced at the expense of its substance, usually internal, 

 less often external. The movement of these pseudopodia is ordinarily 

 slow, but sometimes more rapid, acting as arms to extend the 

 organism to any neighbouring locality where the conditions may be 

 especially favourable for its nutrition. 



During the growth of the pseudopodia cavities are formed inside 

 it through which circulate a variety of nutrient fluids, one of these 

 being the chlorophyll-pigment, though many phytoblasts are entirely 

 destitute of it. Another frequent product of the phytoblast is the 

 phytocyst, an external envelope of cellulose, mixed with a certain 

 proportion of the superficial proteid substance ; but which must be 

 regarded only as a kind of carapace belonging to the moneroid 

 structure which represents the phytoblast. 



A favourable object for observing the structure and movements of 

 these pseudopodia is the hairs at the base of the stamens of 

 FicoideaB ; within which are seen, in favourable conditions, proto- 

 plasmic structures with a rapid oscillating motion resembling that 

 of vibratile cilia. These pseudopodia coalesce when they meet, and 

 the internal microsomes move rapidly from one to another. The 

 author compares this movement to that of plasmodia, and regards 

 it as forming an argument in favour of the animal nature of these 

 phytoblasts or phytozoaires. 



Formation of Pollen-tubes. t — J.B. Schnetzler places pollen-grains 

 of Narcissus poeticus in the mucilage from the stem of the plant. 

 After about two hours, pollen-tubes begin to be formed, in which, at 

 a temperature of 13° C, currents of protoplasm are very evident. The 

 tubes thus formed vary greatly in form and dimension, while those 



* Bull. Soc. Linn, de Paris, 18S2, pp. 297-8 and 313-4. 

 t Bot. Centralbl., xi. (1882) pp. 104-5. 



