234 THE PHYSIOLOGY OF REPRODUCTION 



larva- in organisation. But Bullot 1 showed that in another Annelid, 

 Ophelia, ova fertilised by hypertonic sea-water underwent a regular 

 segmentation. 



Loeb has shown that the ova of limpets (Acmcw and Lottia) could 

 be artificially fertilised by the combined action of fatty acid and 

 hypertonic sea-water. This method also had the effect of hastening 

 maturation, since ova which could not be fertilised by spermatozoa 

 could be made to develop into larvte by the artificial treatment. It 

 was found, further, that maturation could be induced by the action 

 of alkaline sea-water, and that ova which were treated in this way 

 could be fertilised by spermatozoa or artificially fertilised. 2 



Bataillon 3 states that the unfertilised eggs of the lamprey, and 

 also those of the frog, can be made to undergo segmentation as far as 

 the morula stage by depositing them in a salt solution of such a 

 concentration that they lose water. Sugar solutions were also found 

 to be effective. 4 The unfertilised eggs of the frog can be made to 

 segment also, and in many cases to develop into tadpoles and even 

 to undergo metamorphosis by puncturing them with a needle. 5 



Various experiments have been tried with the object of finding 

 out whether ova could be fertilised by substances artificially extracted 

 from spermatozoa, but so far without any positive result. 6 Thus Gies 

 attempted to obtain an enzyme from spermatozoa, with a view to 

 seeing if such a substance would exert any influence on the unfertilised 

 ovum, but his experiments lent no support to the idea. 7 Pizon's 8 

 experiments on the same question were also negative in result. 

 (See p. 317.) 



Loeb 9 has discussed at some length the question as to whether 

 any idea can be formed regarding the nature of the action of the 

 spermatozoon in causing the ovum to develop. He stated his belief 

 that the essential effect of the spermatozoon consists in the trans- 

 formation of part of the protoplasmic or reserve material in the egg 

 into the specific nuclein or chromatin substance of the nucleus. In 



1 Bullot, "Artificial Parthenogenesis and Regular Segmentation in an 

 Annelid (Ophelia)" Arch. f. Entwick.-Mechanik, vol. xviii., 1904. 



- Loeb, Univ. of California Publications : Physiology, Berkeley, vol. i., 1903, 

 and vol. iii., 1905. 



3 Bataillon, "Nouveaux Essais de Parth6nogenese experiinentale chez lea 

 Vertebres inf6rieurs (Rana frisca et Petromyzon planeri)", Arch. f. Entirick.- 

 Mechanik, vol. xviii., 1904. 



4 Loeb, loc. cit. 



6 For an account of the experiments and further references see Loeb, 

 Artificial Parthenogenesis and Fertilisation, Chicago, 1913. 



6 See Loeb, The Dynamics of Living Natter, New York, 1906. 



7 Gies, " Do Spermatozoa contain Enzyme having the Power of causing 

 Development of Mature Ova ?" Amer. Jour, of PhysioL, vol. vi., 1901. 



8 Pizon, " Eecherches sur une pretendue Ovulase des Spermatozoides," 

 C. R. de VAcad. des Sciences, vol. cxli., 1905. 



9 Loeb, loc. cit.' 



