paired pores represent these. The ripe eggs are spherical to pear- 

 shaped xn form and sandy to light tan in color „ At the time of 

 extrusion- they are non -buoyant and someTrfiat adhesive] sand grains 

 stick to them readily,, 



« 



In order to deterrrdne the nature cf the ova present through- 

 out a given ovary ;, and the degree of egg development (ioe.^ stage 

 cf maturity) in females at different times durxng the spaiming 

 run_, diameter measurements of ova were made from eight specimens. 

 Measurements ivere made by means of an ocular micrometer in a com- 

 pound binocular microscope; calibration of the ocular micrometer 

 ivith stage micrometer indicated a value of 0.05 millimeters for 

 each micrometer unitj diameters were therefore determined to the 

 nearest 0,05 millimeter „ 



Due to the effects of preservation and the natural shape cf 

 many of the eggs, very few were perfectly symmetrical. In order 

 to avoid any selection of the longest or shortest diameter^ the 

 micrometer was fixed in a vertical position upon the field of 

 vision and the diameter parallel to the graduations on the microm- 

 eter measured. This gave the longest diameter of some eggSj the 

 shortest of others, or intermediate meastirements between the two. 

 Clark (1925) tested this method and found it to be reliable. It 

 was used again by the same author (Clark, 193h) and by Carbine. 

 {19hh) "vvith excellent results. Although the eggs appeared equally 

 turgid and i-rell~formed both after preservation and when examined 

 fresh, I do not know if any small shrinkage occiirred because of 

 preservation. If any did occur, it could hardly have been an 

 appreciable amount. In any eventj the relative values obtained 

 would keep their identity. 



The first ovary analyzed was from a 12„ 6-inch (320 mm.) female 

 taken in the Carp Creek weir on June 16, 19U7= The weight of this 

 female was 70 grams and the ovary weighed 13.^0 grams or 19.2 per- 

 cent of the weight of the specimen. Sections ivere removed from the 

 anterior, middle, and posterior thirds of the ovary. The eggs were 

 teased out of the sections, a random sample of 5'00 eggs was obtained, 

 and these eggs were measured... A frequency diagram of these ova 

 measurements appears in Figure 2i4.. For each secoion^ the average 

 diameter and range irvere as follows: 



Anterior section -averages 0,87 mm,, range; 0,3^-1,10 mm. 

 Midsection -average: O.9O mm., range: 0.50~l„l5 mm. 

 Posterior section-average; 0.82 mm., range: 0.35-l«l5 nim« 



It is apparent from these data that the ova in the midportibn of the 

 ovary are slightly larger than those developing in the front and 

 back portions. The difference is so small, hoivever, 0.03 millimeters 

 and 0,08 mi.llimeter3, that no appreciable error is involved in the 

 other measxirem^ents and calculations made from midsections only. 



73 _ 



