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These nine cases are all that have been tried between these 

 genera, so far as we know, and all have had the same result, 

 being the rule and not the exception ; whereas the Cypripedium 

 cases were but a few curiosities out of hundreds of normal 

 hybrids, and therefore the exception rather than the rule. With 

 regard to the suggestion of parthenogenesis I cannot deny that 

 Mr. Grey's cross between Phragmipedium and Paphiopedium 

 might possibly be due to this, especially as the plant closely 

 resembled the mother parent variety as well as species, and only 

 differed but slightly in size of flower. Parthenogenesis, or the 

 production of fertile seeds in a pod without the aid of pollen, 

 is well known to occur in certain plants (see Kerner and Oliver, 

 " Natural History Plants," ii. p. 469 ; Gardeners' Chronicle, 

 August 23, 1890, p. 218) ; and Prof. Henslow in his " Structure 

 of Flowers," p. 171, refers to an interesting discovery acci- 

 dentally made by Dr. Treub. Dr. Treub found a larva of an 

 insect in the ovary of a Mauritian Orchid, Liparis latifolia : it did 

 not injure either the ovules or the ovary, but seemed to feed on 

 the juices secreted by the ovarian cavity. In this cavity, without 

 the aid of pollen, the ovules developed and became covered with 

 seed-coats, as if under the influence of pollination, so that the 

 irritation of the larva determined the development of the ovules 

 in the same way that the pollen tubes would have done. 



This possibly may have happened with Mr. Grey's plant. The 

 pollen tubes of Paph. Stonei may have irritated and developed 

 the ovules by feeding on the juices of the pod, and in some way 

 failed to fertilise the egg-cell, the result being a seed-bud 

 developed within the pod bearing the characters of the mother 

 species and the mother variety. But it is not fair or proper to 

 generalise from an isolated instance like this ; we must wait 

 patiently for further results before we attempt to assign or 

 determine the real cause of this curiosity. 



But in the case of the Zygopetalum crosses we can make 

 more sure of our ground. If these were caused by parthenogenesis 

 all the plants would be alike from one pod ; but this was not so, 

 for Mr. Soden writes to me that " all the seedlings varied, the 

 same as all imported plants in size and colour," and we know 

 that one of Mr. Treseder's plants differed in colour from its 

 birth-mates, 11 the lip being almost wholly white, with a few 

 slight purple marks at base and centre, and the margin was 



