ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 261 



processes to correspond closely to those already described by Hegel- 

 maier,* tbe details being given in each case. He found the alcoholic 

 preparation of young ovules not favourable for observation, dis- 

 organized conditions only being presented in the interior of the 

 embryo-sac. With fresh material, fortimate sections sometimes ex- 

 hibited the phenomena very clearly ; the best results were obtained 

 with the assistance of 1 per cent, chromic acid. The ovary was not 

 opened before laying in the solution. After several days, it was 

 washed with distilled water, and placed in a mixture of glycerine and 

 alcohol. All the preparations were tinged with borax-carmine. 



Embryology of OrcMs maculata.t — From an examination of the 

 structure and development of the embryo in this species, M. Monte- 

 verde confirms the statement of Pfitzer (in opposition to that of Hof- 

 meister and Fleischer), that it proceeds, not from a single cell, but from 

 three or four of the cells of the suspensor, in which longitudinal walls 

 are produced in the form of a cross. Each of the layers formed in this 

 way divides into four central and four peripheric cells ; the latter are 

 not equivalent to the dermatogen. The suspensory cell which is 

 nearest to the embryo, the third or fourth of the primordial cells, is 

 the hypophysis. 



In its earliest stage the embryo of Orchis maculata is composed of 

 two cells of unequal size, an upper smaller, and a lower cell nearly 

 double its size. This last is divided by a second transverse wall into a 

 smaller middle and a larger lower cell ; these two walls are usually 

 inclined to one another. The first longitudinal division then makes 

 its appearance in the upper cell, dividing it into two equal, or less 

 often unequal parts. A new transverse division next appears in the 

 lower cell, and at the same time a second longitudinal division in the 

 middle cell. In the two lower cells the succeeding transverse divisions 

 are formed in an intercalary manner, so that four cells are produced, 

 each of which is divided afresh into two by transverse walls, though 

 this is not always the case. Of these eight cells, the seven lower ones 

 constitute the suspensor, and subsequently perish, while the upper- 

 most takes part in the formation of the embryo. 



A comparison of the first stages of development of the embryo 

 of Orchis maculata with those of other Monocotyledons, for example, 

 Brachypodium, as described by Hanstein, shows a very close resem- 

 blance, not only in their general character, but also in the relative 

 position of the two first transverse walls, in the appearance of the two 

 longitudinal walls of the two upper cells, and finally in the fact that 

 one of the cells often assumes the appearance of a terminal cell. 



The third cell, which is usually regarded as the hypophysis, also 

 takes its share, with the two superior cells, in the formation of the 

 embryo. As a rule, this cell, after having divided by a transverse 

 wall, produces in its upper part one or two longitudinal divisions 

 arranged in a cross, and always remains in this state until the seed 

 is mature. 



* See this Journal, iii. (1880) p. 979. 



t Bull. Acad. Imp. St. Petersburg, xxvii. (1880) pp. 326-35. 



