VI 



Professor Owen to express the dissimilar Digenesis or Alternation 

 of Generations. 



That the same thing occurs in other species of animals 

 besides those upon which the author's observations have been 

 made, there can be no doubt, and, in fact, several of these are 

 indicated in his concluding remarks. Of some of the Ento- 

 mostracous Crustacea no males have yet been detected, whilst 

 the females of others have been observed to propagate without 

 concourse with the male. A still more striking instance is 

 afforded by the Gall-flies belonging to the restricted genus 

 Cynips, of which several species are very common in Europe, 

 and yet amongst the thousands which have been reared from 

 galls, not a single male has ever been seen. An oak-gall has 

 been found in great quantities of late in Devonshire, which has 

 attracted considerable attention from those few Entomologists 

 in this country who trouble themselves with the study of 

 Hymenoptera. It is produced by a species of Cynips, and all 

 the specimens, to the number of several hundreds, which have 

 been reared, confirm the above statement as to the absence of 

 males. Some experiments now being made by Mr. Smith of 

 the British Museum, whose tact and power of observation so 

 thoroughly fit him for the investigation of such a point, will 

 probably soon determine whether these Insects are also to be 

 cited in support of the interesting and important theory 

 developed by Von Siebold in the following pages. Amongst 

 the Entozoa, we may also probably meet with further instances 

 of Parthenogenesis, as their propagation, notwithstanding the 

 great advances that have of late been made in our knowledge 

 of its phenomena, still presents much that is enigmatical. 



But it is not only in the Animal Kingdom that w r e meet with 

 this phenomenon of ovular reproduction without impregnation : 

 similar instances occur also amongst the Phanerogamous plants. 

 Many years ago, Camerarius and Spallanzani asserted that the 

 female Hemp was capable of producing fertile seed without the 

 aid of the male pollen ; and a French botanist, M. Lecoq, has 

 lately addressed a note to the Academy of Sciences, referring to 

 some experiments made by him, and published in 1827, upon 

 the same subject. His experiments were made upon various 

 dioecious plants, amongst which Hemp, Spinach, Mercurialis 



