226 EMBRYOLOGY. [BOOK 11. 



from the boxes in which it is naturally locked up, it seemed 

 that the mode of fertilisation in Orchids was still unsettled ; 

 and it must be admitted that the agency of insects, to which 

 Brown had recourse in order to make out his case, was 

 scarcely reconcileable with his supposition that the insect 

 forms, which in Ophrys are so striking, and which, he says, 

 resemble the insects of the countries in which the plants are 

 found, ee are intended rather to repel than to attract." But 

 although such arguments were not unobjectionable, it is, 

 nevertheless, certain that Orchids require contact to take 

 place between their pollen and stigma, in order to insure 

 fertilisation. This has been shown by Professor Morren, 

 and has now become in gardens a matter of notoriety. 



Conflicting statements as to what really occurs when the 

 embryo is first generated in the amniotic sac, have for 

 several years occupied the attention of Botanists. To enter 

 into any discussion of the respective value of these state- 

 ments would be less advantageous to the student than the 

 record of the observations actually made by excellent and 

 trustworthy observers. The real phenomena are explained 

 in the following cases, described by botanists familiar with 

 the microscope and expert in anatomical examination. 



In the nineteenth volume of the Linnaean Transactions, 

 Dr. Herbert Giraud has published the following very detailed 

 account of facts observed by him in Tropaeolum majus, a 

 plant whose parts present peculiar facilities for examination. 

 They are arranged under seven general heads, corresponding 

 with as many progressive periods in the growth of the 

 so-called female organs, extending from the completion of 

 the anatropal development of the ovule, to the perfect 

 formation of the embryo : or from the commencement of the 

 expansion of the bud, to the complete formation of the fruit. 



"First Period. On making a section of a carpel (just 

 before the expansion of the bud), from its dorsum inwards 

 towards the axis of the pistil, and in the direction of that 

 axis, the solitary ovule is at the same time divided, and is 

 found to have completed its anatropous development. Con- 

 tinuous with that part of the columella which forms the 



