Differences Demonstrate Refined Structural Neuron Proof Quality Lacking

意群训练： It was possible to demonstrate by other methods refined structural differences among neuron types ; however , proof was lacking that the quality of the impulse or its condition was influenced by these differences , which seemed instead to influence the developmental patterning of the neural circuits.

标志： It was possible to demonstrate /by other methods/ refined structural differences (among neuron types); however , proof was lacking ［that the quality (of the impulse) or its condition was influenced /by these differences/, (which seemed instead to influence the developmental patterning of the neural circuits )］.

译文： 有 可能 /通过其他方法/来 证明 （神经元种类间的）细微的结构差异 ；可是， 这样的 证据 是 缺乏的 ，［即 （神经冲动的）性质或状态 是 /受这些差异/所影响的 ，（而 这些差异 看起来 却能 影响神经网络的发育模式 ）］。

解释： 与很多人的印象相反，lack从来就不能做形容词：它只有动词或名词的词性。其形容词的形式是lacking，意思是缺乏的，不足的。

本句的在however之前和之后的两个分句，是两个倒装结构，前一个是小倒装，正常语序是：to demonstrate refined structural differences (among neuron types) /by other methods/；however后面是个大倒装，lacking之后的that引导的同位语从句是修饰主语proof 的，但是因为它太长，所以为了避免头重脚轻，被放到了lacking之后。正常的语序应该是proof that the quality of...was lacking。