188 ARTIFICIAL PARTHENOGENESIS 



and any variations in the prescribed technique. If, perchance, you achieve an unusually 

 high percentage of cleavages, you will want to be able to repeat the procedure in every 

 detail. 



There are qualitative aspects of the problem which should be recorded under: 



1. Pattern of cleavage when it is not normal. Is the injury point In any way 

 related to the position of the cleavage furrow or the position of the grey 

 crescent? 



2. Bate of cleavage . This observation will have value only if the temperature for 

 the experimentals and controls Is identical. 



5. Analysis of haploid characteri sties of the tadpoles which develop. These in- 

 clude microcephaly (due to sluggish or Incomplete gastrulatlon) ; dorsal flex- 

 ion of head and tall; increased number of cells per unit area (except the 

 notochord) ; and frequent oedema which Is thought to be due to the malfunction- 

 ing of the excretory system of haplold tadpoles. Oedema alone is not an ade- 

 quate criterion for there are many environmental factors which will cause this 

 condition in normally diploid tadpoles. 



h. Fix and stain tail tips of parthenogenetlc tadpoles 9 to 10 days old to make 

 chromosome counts. (See under Tail Tip Technique.) 



Many of the parthenogeneti cally activated eggs will proceed to early stages of 

 development and then cytolyze. It would be instructive to make a rapid preparation of a 

 healthy neurula stage to determine whether the cells are truly haplold, using the method 

 of Tyler (l9'+6). This simply Involves placing the neurula on a coverslip; separating or 

 teasing apart its cells In a minimum amount of culture medium, possibly with the aid of 

 0.1^ KOH; inverting the coverslip over a second coverslip on which is placed a large drop 

 of Bouin's fixative. The edges of the upper coverslip should cross the corners of the 

 lower coverslip so that they can be separated the more easily after fixation. If the 

 coverslipa are moved over each other slightly, this will separate the cells of the neurula 

 and they will become fixed and moat of them will become attached to one of the coverellps. 

 After 5 minutes, place the paired coverallps in a Syracuse dish of Bouin's fluid and gent- 

 ly tease them apart with needles. Allow the fixative to act another 5 minutes. From this 

 point on the coverslipa may be treated as any mounted cytological preparation, and may be 

 stained for chromosomes. It should be possible to locate some mitotic figures in the 

 neural crest cells which will answer the question relative to ploidy. 



In general the frog's egg lenda itself admirably to this type of experiment. The 

 results should give from 0^ to 18^ cleavages, with the average about 6^. The eggs which 

 show relatively normal cleavages should be isolated and given apeclal care In the hope 

 that aome may develop into tadpoles. 



BEFERENCES : 



Bataillon, E., 1929 - "Analyse de la fecondation par la pathenogenese experlmentale." 



Arch. f. Ent. mech. 115:711. 

 Dalcq, A., I928 - "Les Bases Physiologlquea de la Fecondation et de la Parthenogenese." 



Les Problemes Blologlques, Paris. 

 Harvey, E. B. , 19^+0 - "Development of half-eggs of Arbacia punctulata obtained by cen- 



trlfuging after fertilization, with special reference to parthenogenetlc merogony." 



Biol, Bull, 78:'+12. 

 Just, E. E,, 1959 - "The Biology of the Cell Surface." Blakiston, 

 Lillle, B. S., 19'*-1 - "Further experiments on artificial parthenogenesis in starfish eggs 



with a review," Physiol. Zool, l'+:259. 

 Loeb, J., 1921 - "Further observations on the production of parthenogenetlc frogs." Jour. 



Gen. Physiol. 5:529. 

 Parmenter, C. L., I9U0 - "Chromosome numbers in Sana fusca parthenogeneti cally developed 



from eggs with known polar body and cleavage histories." Jour. Morph. 66:2l4-l. 

 Pincus, G. & H. Shapiro, I9U0 - "The comparative behavior of mammalian eggs in vivo and 



in vitro. VII. Further studies on the activation of Babbit eggs." Proc. Am. Phil. 



Soc. 85:651. 

 Boatand, J., 1958 - "La Parthenogenese des Vertebres," Actualities Sclentifiques er 



Industrielles. 651:5 (Herman er Ci, Paris). 



